A drug class is a method of identifying and grouping drugs by chemical type, active ingredients, or by medical condition it treats. A drug may belong in more than one drug class.
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"Beta-Adrenergic antagonist" redirects here
Beta blockers (sometimes written as β-blockers) or beta-adrenergic blocking agents, beta-adrenergic antagonists, beta-adrenoreceptor antagonists or beta antagonists, are a class of drugs used for various indications. They are particularly used for the management of cardiac arrhythmias, cardioprotection after myocardial infarction (heart attack), and hypertension. As beta adrenergic receptor antagonists, they diminish the effects of epinephrine (adrenaline) and other stress hormones. In 1958, the first beta blocker, dichloroisoproterenol, was synthesised by Eli Lilly Laboratories, but Sir James W. Black in 1962, found the first clinically significant beta blockers - propranolol and pronethalol; it revolutionized the medical management of angina pectoris and is considered by many to be one of the most important contributions to clinical medicine and pharmacology of the 20th century.
Beta blockers block the action of endogenous catecholamines epinephrine (adrenaline) and norepinephrine (noradrenaline) in particular, on β-adrenergic receptors, part of the sympathetic nervous system which mediates the fight-or-flight response. Three types of
Bisphosphonates (also called diphosphonates) are a class of drugs that prevent the loss of bone mass, used to treat osteoporosis and similar diseases. They are the most commonly prescribed drugs used to treat osteoporosis. They are called bisphosphonates because they have two phosphonate (PO3) groups and are similar in structure to pyrophosphate.
Evidence shows that they reduce the risk of osteoporotic fracture in those who have had previous fractures. However, they do not reduce fracture risk in those with osteoporosis who have not previously had a fracture.
Bone undergoes constant turnover and is kept in balance (homeostasis) by osteoblasts creating bone and osteoclasts destroying bone. Bisphosphonates inhibit the digestion of bone by encouraging osteoclasts to undergo apoptosis, or cell death, thereby slowing bone loss.
The uses of bisphosphonates include the prevention and treatment of osteoporosis, osteitis deformans ("Paget's disease of bone"), bone metastasis (with or without hypercalcaemia), multiple myeloma, primary hyperparathyroidism, osteogenesis imperfecta, and other conditions that feature bone fragility.
Most doctors use bisphosphonates to treat osteoporosis,
Monoclonal antibodies (mAb or moAb) are monospecific antibodies that are the same because they are made by identical immune cells that are all clones of a unique parent cell, in contrast to polyclonal antibodies which are made from several different immune cells. Monoclonal antibodies have monovalent affinity, in that they bind to the same epitope.
Given almost any substance, it is possible to produce monoclonal antibodies that specifically bind to that substance; they can then serve to detect or purify that substance. This has become an important tool in biochemistry, molecular biology and medicine. When used as medications, the non-proprietary drug name ends in -mab (see "Nomenclature of monoclonal antibodies").
The idea of a "magic bullet" was first proposed by Paul Ehrlich, who, at the beginning of the 20th century, postulated that, if a compound could be made that selectively targeted against a disease-causing organism, then a toxin for that organism could be delivered along with the agent of selectivity. He and Élie Metchnikoff received the 1908 Nobel Prize for Physiology or Medicine for this work, which led to an effective syphilis treatment by 1910.
In the 1970s, the B-cell
An anxiolytic (also antipanic or antianxiety agent) is a drug used for the treatment of anxiety and its related psychological and physical symptoms. Anxiolytics have been shown to be useful in the treatment of anxiety disorders.
Beta-receptor blockers such as propranolol and oxprenolol, although not anxiolytics, can be used to combat the somatic symptoms of anxiety.
Anxiolytics are also known as minor tranquilizers. The term is less common in modern texts, and was originally derived from a dichotomy with major tranquilizers, also known as neuroleptics or antipsychotics.
Benzodiazepines are prescribed for short-term relief of severe and disabling anxiety. Benzodiazepines may also be indicated to cover the latent periods associated with the medications prescribed to treat an underlying anxiety disorder. They are used to treat a wide variety of conditions and symptoms and are usually a first choice when short-term CNS sedation is needed. Longer-term uses include treatment for severe anxiety. There is a risk of a benzodiazepine withdrawal and rebound syndrome after continuous usage for longer than two weeks, and tolerance and dependence may occur if patients stay under this treatment
The bile acid sequestrants are a group of resins used to bind certain components of bile in the gastrointestinal tract. They disrupt the enterohepatic circulation of bile acids by combining with bile constituents and preventing their reabsorption from the gut. In general, they are classified as hypolipidemic agents, although they may be used for purposes other than lowering cholesterol. They are used in the treatment of chronic diarrhoea due to bile acid malabsorption.
Since bile acids are biosynthesized from cholesterol, disruption of bile acid reabsorption will decrease cholesterol levels, in particular, low-density lipoprotein (commonly known as "bad cholesterol"). Therefore, they may be used for the treatment of hypercholesterolemia and dyslipidemia.
In chronic liver diseases such as cirrhosis, bile acids may deposit in the skin, causing pruritus (itching). Hence, bile acid sequestrants may be used for the prevention of pruritus in patients with chronic liver disease.
In addition, diarrhea may be caused by excess bile salts entering the colon rather than being absorbed at the end of the small intestine (the ileum). The condition of bile acid malabsorption occurs after surgery
Proton-pump inhibitors (PPIs) are a group of drugs whose main action is a pronounced and long-lasting reduction of gastric acid production. They are the most potent inhibitors of acid secretion available today. The group followed and has largely superseded another group of pharmaceuticals with similar effects, but different mode-of-action, called H2-receptor antagonists. These drugs are among the most widely-selling drugs in the world and are generally considered effective. The vast majority of these drugs are benzimidazole derivatives; however, promising new research indicates that imidazopyridine derivatives may be a more effective means of treatment. High dose or long-term use of PPIs carry a possible increased risk of bone fractures.
These drugs are utilized in the treatment of many conditions such as:
Specialty professional organizations recommend that patients take the lowest effective dose possible to achieve the desired therapeutic result when using proton pump inhibitors to treat gastroesophageal reflux disease long-term. The FDA advises that no more than three 14-day treatment courses should be used in one year.
The effectiveness of proton pump inhibitors has not been
An analgesic (also known as a painkiller) is any member of the group of drugs used to relieve pain (achieve analgesia). The word analgesic derives from Greek αν - ("without") and άλγος - ("pain").
Analgesic drugs act in various ways on the peripheral and central nervous systems; they include paracetamol (para-acetylaminophenol, also known in the US as acetaminophen or simply APAP), the non-steroidal anti-inflammatory drugs (NSAIDs) such as the salicylates, and opioid drugs such as morphine and opium. They are distinct from anesthetics, which reversibly eliminate sensation.
In choosing analgesics, the severity and response to other medication determines the choice of agent; the WHO pain ladder, originally developed in cancer-related pain, is widely applied to find suitable drugs in a stepwise manner. The analgesic choice is also determined by the type of pain: for neuropathic pain, traditional analgesics are less effective, and there is often benefit from classes of drugs that are not normally considered analgesics, such as tricyclic antidepressants and anticonvulsants.
The exact mechanism of action of paracetamol/acetaminophen is uncertain, but it appears to be acting centrally
Vitamin K is a group of structurally similar, fat-soluble vitamins that are needed for the posttranslational modification of certain proteins required for blood coagulation and in metabolic pathways in bone and other tissue. They are 2-methyl-1,4-naphthoquinone (3-) derivatives. This group of vitamins includes two natural vitamers: vitamin K1 and vitamin K2.
Vitamin K1, also known as phylloquinone or phytomenadione (also called phytonadione), is synthesized by plants, and is found in highest amounts in green leafy vegetables because it is directly involved in photosynthesis.
Vitamin K2 has several subtypes, one of which is involved in bone metabolism. Vitamin K2 homologs (menaquinones) are characterized by the number of isoprenoid residues in their side chain. Menaquinones are abbreviated MK-n, where n represents the number of isoprenoid side chain residues. For example, menaquinone-4 (abbreviated MK-4), has four isoprene residues in its side chain. Bacteria in the colon (large intestine) can produce a range of vitamin K2 forms, and can also convert K1 into K2 (MK-7 homolog). No known toxicity exists for vitamins K1 or K2.
Three synthetic types of vitamin K are known: vitamins K3,
Lincosamides (e.g. lincomycin, clindamycin) are a class of antibiotics.
Lincosamides prevent bacteria replicating by interfering with the synthesis of proteins. They bind to the 23s portion of the 50S subunit of bacterial ribosomes and cause premature dissociation of the peptidyl-tRNA from the ribosome. Lincosamides do not interfere with protein synthesis in human cells (or those of other eukaryotes) because human ribosomes are structurally different from those of bacteria.
The first lincosamide to be discovered is lincomycin, isolated from Streptomyces lincolnensis in a soil sample from Lincoln, Nebraska (hence the bacterial name).
Lincomycin has been superseded by clindamycin, which exhibits improved antibacterial activity. Clindamycin also exhibits some activity against parasitic protozoa, and has been used in toxoplasmosis and malaria.
They are normally used to treat staphylococci and streptococci, and have proved useful in treating Bacteroides fragilis and some other anaerobes. They are used in the treatment of Toxic Shock Syndrome and thought to directly block the M protein production that leads to the severe inflammatory response.
Target bacteria may alter the drug's binding
Pediculicides are substances used to treat lice (Pediculus humanus capitus).
Today, insecticides used for the treatment of head lice include organochlorines (lindane), organophosphates (malathion), carbamates (carbaryl), pyrethrins (pyrethrum), and pyrethroids (permethrin, phenothrin, bio-allethrin).
The only agents approved by the FDA for treatment of pediculosis are lindane and malathion.
Laboratory and clinical studies found that many of the pediculicides in the market are either not fully effective or are ineffective when they are used according to the instructions.
Pediculicides may rapidly lose their efficacy because of the development of resistance. Resistance of head lice to insecticides such as lindane, malathion, phenothrin and permethrin has been reported.
Ivermectin (which can be given orally) has been shown to reduce levels of louse infestation. Originally approved for onchocerciasis and strongyloidiasis, Ivermectin is now approved by the FDA for pediculosis.
Natural products tested clinically and found to be safe and effective could be very important in the control of head lice, as the complexity of the active ingredients may prevent the rapid development of
A class of natural or synthetic sulfanilamide derivatives with antibacterial activity. Sulfonamides are structural analogues of para-aminobenzoic acid (essential for microbial folate synthesis). Sulfonamides inhibit bacterial metabolism by competing with PABA for dihydropteroate synthase, thereby resulting in disruption of folic acid metabolism and ultimately DNA synthesis.
Vasopressin analogues are chemicals similar in function but not necessarily similar in structure to vasopressin (ADH), such as desmopressin.
Desmopressin is administered as an oral spray to treat diseases where ADH is either not being produced in sufficient amounts, or vasopressin's receptors are not being stimulated by the vasopressin. An example of desmopressin's use is for childhood bed-wetting, where it is believed that children's circadian rhythms are not synchronized with normal light-dark cycles, and consequentially the ADH surge normal children experience at night is not experienced in these children. Taking a desmopressin dose 30–45 minutes before sleeping results in concentrated urine production, and the urination reflex experienced when the bladder fills above a certain level is not triggered.
See also the article 2- and 4-Quinolones which includes additional discussion of the quinolone antibacterial class.
The quinolones are a family of synthetic broad-spectrum antibacterial drugs The first generation of the quinolones begins with the introduction of nalidixic acid in 1962 for treatment of urinary tract infections in humans. Nalidixic acid was discovered by George Lesher and coworkers in a distillate during an attempt at chloroquine synthesis.
They prevent bacterial DNA from unwinding and duplicating. (See Mechanism of Action)
Quinolones, in comparison to other antibiotic classes, have among the highest risk of causing colonization with MRSA and Clostridium difficile. The majority of quinolones in clinical use belong to the subset fluoroquinolones, which have a fluorine atom attached to the central ring system, typically at the 6-position or C-7 position.
Fluoroquinolones are broad-spectrum antibiotics that play an important role in treatment of serious bacterial infections, especially hospital-acquired infections and others in which resistance to older antibacterial classes is suspected. Because the use of broad-spectrum antibiotics encourages the spread of multidrug
Direct thrombin inhibitors (DTIs) are a class of medication that act as anticoagulants (delaying blood clotting) by directly inhibiting the enzyme thrombin. Some are in clinical use, while others are undergoing clinical development. Several members of the class are expected to replace heparin (and derivatives) and warfarin in various clinical scenarios.
There are two types of DTIs, dependent on their interaction with the thrombin molecule. Bivalent DTIs (hirudin and analogs) bind both to the active site and exosite 1, while univalent DTIs bind only to the active site.
Hirudin and derivatives were originally discovered in Hirudo medicinalis:
Univalent DTIs include:
Bivalent DTIs enjoy limited use in circumstances where heparin would be indicated such as the acute coronary syndrome ("unstable angina"), but cannot be used. As they are administered by injection (intravenous, intramuscular or subcutaneous), they are less suitable for long-term treatment.
Argatroban (as well as the hirudins) are used for heparin-induced thrombocytopenia, a rare but serious complication of heparin treatment that requires anticoagulation (as it increases both arterial and venous thrombosis risk) but not
An adrenergic agent is a drug, or other substance, which has effects similar to, or the same as, epinephrine (adrenaline). Thus, it is a kind of sympathomimetic agent. Alternatively, it may refer to something which is susceptible to epinephrine, or similar substances, such as a biological receptor (specifically, the adrenergic receptors).
Adreneric agonists stimulate a response from the adrenergic receptors. The five categories of adrenergic receptors are: α1, α2, β1, β2, and β3, and agonists vary in specificity between these receptors, and may be classified respectively. However, there are also other mechanisms of adrenergic agonism. Epinephrine and norepinephrine are endogenous and broad-spectrum. More selective agonists are more useful in pharmacology.
Directly acting adrenergic agonists act on adrenergic receptors. All adrenergic receptors are G-protein coupled, activating signal transduction pathways. The G-protein receptor can affect the function of adenylate cyclase or phospholipase C, an agonist of the receptor will upregulate the effects on the downstream pathway (it will not necessarily upregulate the pathway itself).
The receptors are broadly grouped into α and β
Ampakines are a class of compounds known to enhance attention span and alertness, and facilitate learning and memory. The ampakines take their name from the glutamatergic AMPA receptor with which they strongly interact. The AMPA receptor, in turn, gets its name from AMPA, which selectively binds to it.
Ampakines have been investigated by DARPA for potential use in increasing military effectiveness.
Unlike earlier stimulants (e.g. caffeine, methylphenidate (Ritalin), and the amphetamines), ampakines do not seem to have unpleasant, long-lasting side effects such as sleeplessness.
They are currently being investigated as potential treatment for a range of conditions involving mental disability and disturbances such as Alzheimer's disease, Parkinson's disease, schizophrenia, Treatment-resistant depression (TRD) or neurological disorders such as Attention Deficit Hyperactivity Disorder (ADHD), among others. In a 2006 study they were shown to have an effect after they had left the body, continuing to enhance learning and memory.
Ampakine activity has been established as one of the modes of action of the well established class of nootropics, the racetam drugs such as piracetam,
In organic chemistry carboxamides (or amino carbonyls) are functional groups with the general structure R-CO-NH2 with R as an organic substituent.
Two amino acids, asparagine and glutamine, have a carboxamide group in them.
Monoamine oxidase inhibitors (MAOIs) are a class of medications prescribed for the treatment of depression. They are particularly effective in treating atypical depression.
Because of potentially lethal dietary and drug interactions, monoamine oxidase inhibitors have historically been reserved as a last line of treatment, used only when other classes of antidepressant drugs (for example selective serotonin reuptake inhibitors and tricyclic antidepressants) have failed. A transdermal patch form of the MAOI selegiline, called Emsam, was approved for use by the Food and Drug Administration in the United States on February 28, 2006.
In the past, MAOIs were prescribed for those resistant to tricyclic antidepressant therapy, but newer MAOIs such as selegiline (typically used in the treatment of Parkinson's disease) and the reversible MAOI moclobemide provide a safer alternative and are now sometimes used as first-line therapy, although these substances are not always as effective as their predecessors.
MAOIs have been found to be effective in the treatment of panic disorder with agoraphobia, social phobia, atypical depression or mixed anxiety and depression, bulimia, and post-traumatic
Typical antipsychotics (sometimes referred to as first generation antipsychotics, conventional antipsychotics, classical neuroleptics, traditional antipsychotics, or major tranquilizers) are a class of antipsychotic drugs first developed in the 1950s and used to treat psychosis (in particular, schizophrenia). Typical antipsychotics may also be used for the treatment of acute mania, agitation, and other conditions. The first typical antipsychotics to enter clinical use were the phenothiazines. Second-generation antipsychotics are known as atypical antipsychotics.
Both generations of medication tend to block receptors in the brain's dopamine pathways, but compared to the typicals, the atypicals are less likely to cause extrapyramidal motor control disabilities in patients, which include unsteady Parkinson's disease-type movements, body rigidity and involuntary tremors. These abnormal body movements can become permanent even after medication is stopped.
Traditional antipsychotics are classified as either high-potency or low-potency:
Some of the high-potency antipsychotics have been formulated as the decanoate ester (e.g. fluphenazine decanoate) to allow for a slow release of the
Antifibrinolytics, such as aminocaproic acid (ε-aminocaproic acid) and tranexamic acid are used as inhibitors of fibrinolysis. These lysine-like drugs interfere with the formation of the fibrinolytic enzyme plasmin from its precursor plasminogen by plasminogen activators (primarily t-PA and u-PA) which takes place mainly in lysine rich areas on the surface of fibrin. These drugs block the binding sites of the enzymes or plasminogen respectively and thus stop plasmin formation.
They are used in menorrhagia and bleeding tendency due to various causes. Their application may be beneficial in patients with hyperfibrinolysis because they arrest bleeding rapidly if the other components of the haemostatic system are not severely affected. This may help to avoid the use of blood products such as fresh frozen plasma (FFP) with its associated risks of infections or anaphylactic reactions.
In 2010, the CRASH-2 trial showed that the antifibrinolytic drug tranexamic acid safely reduces mortality in bleeding trauma patients.
The antifibrinolytic drug aprotinin was abandoned after identification of major side effects, especially on kidney.
The indication for use of antifibrinolytic drugs is made
Topical decongestants are decongestants applied directly to the nasal cavity. By applying them directly to the site of action, topical decongestants relieve nasal congestion while reducing the side effects associated with systemically-acting decongestants, such as high blood pressure. Topical decongestants should only be used by patients for a maximum of 3 days in a row, because rebound congestion may occur in the form of rhinitis medicamentosa. Topical decongestants are a common form of nasal relief, due to their quick effects which can clear the sinus in as little as ten seconds.
Topical decongestants are vasoconstrictors, and work by constricting the blood vessels within the nasal cavity.
Direct factor Xa inhibitors ('xabans') are a class of anticoagulant drugs which act directly upon Factor X in the coagulation cascade, without using antithrombin as a mediator.
Direct factor Xa inhibitors are being used clinically. Clinical trials published in journals such as the New England Journal of Medicine and The Lancet have shown promise for these compounds as substitutes for the currently administered vitamin K antagonists or low molecular weight heparin. Advantages of orally administered direct Xa inhibitors lie in the fact that they have a predictable effect, do not require frequent monitoring or re-dosing, are given through the mouth and not by injection and have few (known) drug interactions. Disadvantages include the currently limited prospective experience and the theoretical interactions with statin medication, as they are metabolized at least in part by the same cytochrome enzyme, CYP3A4.
A naturally occurring inhibitor of factor Xa was first reported in 1987. Tuszynski et al. discovered antistasin, which was isolated from the extracts of Mexican leech, Haementeria officinalis. Soon after this, another naturally occurring inhibitor, tick anticoagulant peptide (TAP)
Glycopeptide antibiotics are a class of antibiotic drugs. The class is composed of glycosylated cyclic or polycyclic nonribosomal peptides. Significant glycopeptide antibiotics include vancomycin, teicoplanin, telavancin, bleomycin, ramoplanin, and decaplanin.
This class of drugs inhibit the synthesis of cell walls in susceptible microbes by inhibiting peptidoglycan synthesis. They bind to the amino acids within the cell wall preventing the addition of new units to the peptidoglycan. In particular, they bind to acyl-D-alanyl-D-alanine in peptidoglycan.
Due to their toxicity, use of glycopeptide antibiotics is restricted to patients who are critically ill, who have a demonstrated hypersensitivity to the β-lactams, or who are infected with β-lactam-resistant species. These antibiotics are effective principally against gram-positive cocci. They exhibit a narrow spectrum of action, and are bacteriocidal only against the enterococci. Some tissues are not penetrated very well by glycopeptides, and they do not penetrate into the cerebrospinal fluid.
Glycopeptides used to be the last effective line of defense for cases of Methicillin-resistant Staphylococcus aureus, however several newer
Gonadotrophin-releasing hormone (GnRH) antagonists (receptor blockers) are a class of compounds that are similar in structure to natural GnRH (a hormone made by neurons in the hypothalamus ) but that have an antagonistic effect. GnRH antagonists are peptide molecules that are made up multiple, often synthetically produced amino acids. GnRH antagonists compete with natural GnRH for binding to GnRH receptors, thus decreasing or blocking GnRH action in the body.
GnRH antagonists competitively and reversibly bind to GnRH receptors in the pituitary gland, blocking the release of luteinising hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary. In men, the reduction in LH subsequently leads to rapid suppression of testosterone release from the testes; in women it leads to suppression of estrogen release from the ovaries.
Unlike the GnRH agonists, which cause an initial stimulation of the hypothalamic-pituitary-gonadal axis (HPGA), leading to a surge in testosterone or estrogen levels, GnRH antagonists have an immediate onset of action, rapidly reducing sex hormone levels without an initial surge.
Currently approved GnRH antagonists include the following:
A phosphodiesterase type 5 inhibitor, often shortened to PDE5 inhibitor, is a drug used to block the degradative action of phosphodiesterase type 5 on cyclic GMP in the smooth muscle cells lining the blood vessels supplying the corpus cavernosum of the penis. These drugs are used in the treatment of erectile dysfunction, and were the first effective oral treatment available for the condition. Because PDE5 is also present in the arterial wall smooth muscle within the lungs, PDE5 inhibitors have also been explored for the treatment of pulmonary hypertension, a disease in which blood vessels in the lungs become overloaded with fluid, usually as a result of failure of the left ventricle of the heart.
PDE5 inhibitors are clinically indicated for the treatment of erectile dysfunction. Sildenafil citrate, one of the PDE5 inhibitors, is also indicated for the treatment of pulmonary hypertension. Other PDE5 inhibitors such as tadalafil and vardenafil have been studied as other possible treatments for this disease.
Sildenafil, the prototypical PDE5 inhibitor, was originally discovered during the search of a novel treatment for angina. Studies in 2002 explored its potential for increasing
Biguanide can refer to a molecule, or to a class of drugs based upon this molecule. Biguanides can function as oral antihyperglycemic drugs used for diabetes mellitus or prediabetes treatment. They are also used as antimalarial drugs.
The disinfectant polyaminopropyl biguanide (PAPB) features biguanide functional groups.
Examples of biguanides:
Galega officinalis (French lilac) was used for diabetes treatment in traditional medicine for centuries. In the 1920s, guanidine compounds were discovered in Galega extracts. Animal studies showed that these compounds lowered blood glucose levels. Some less toxic derivatives, synthalin A and synthalin B, were used for diabetes treatment, but after the discovery of insulin they were forgotten for the next several decades. Biguanides were reintroduced into Type 2 diabetes treatment in the late 1950s. Initially phenformin was widely used, but its potential for sometimes fatal lactic acidosis resulted in its withdrawal from pharmacotherapy in most pharmacopeias (in the U.S. in 1977). Metformin has a much better safety profile, and it is the principal biguanide drug used in pharmacotherapy worldwide.
Biguanides do not affect the output of
Immunostimulants, also known as immunostimulators, are substances (drugs and nutrients) that stimulate the immune system by inducing activation or increasing activity of any of its components. One notable example is the granulocyte macrophage colony-stimulating factor.
There are two main categories of immunostimulants:
Many endogenous substances are non-specific immunostimulators. For example, female sex hormones are known to stimulate both adaptive and innate immune responses. Some autoimmune diseases such as lupus erythematosus strike women preferentially, and their onset often coincides with puberty. Other hormones appear to regulate the immune system as well, most notably prolactin, growth hormone and vitamin D.
Some publications point towards the effect of DCA as an immunostimulant of the unspecific immune system, activating its main actors, the macrophages. According to these publications, a sufficient amount of DCA in the human body corresponds to a good immune reaction of the unspecific immune system.
Levothyroxine, also L-thyroxine or T4, is a synthetic form of thyroid hormone (or thyroxine), the hormone normally secreted by the follicular cells of the thyroid gland. Levothyroxine is used to treat thyroid hormone deficiency, and occasionally to prevent the recurrence of thyroid cancer. Like its naturally secreted counterpart, levothyroxine is chemically in the chiral L-form. The related drug dextrothyroxine (D-thyroxine) was used in the past as a treatment for hypercholesterolemia (elevated cholesterol levels) but was withdrawn due to cardiac side-effects.
Thyroxine was first isolated in pure form in 1914 at the Mayo Clinic by Edward Calvin Kendall from extracts of hog thyroid glands. The hormone was synthesised in 1927 by British chemists Charles Robert Harington and George Barger.
Levothyroxine is typically used to treat hypothyroidism. It may also be used to treat goiter via its ability to lower thyroid-stimulating hormone (TSH), a hormone that is considered goiter-inducing.
Dosing must be carefully controlled to achieve TSH levels within the normal reference range. Long-term suppression of TSH values below normal values will frequently cause cardiac side-effects and
A Lipoxygenase inhibitor is a drug that slows down or stops the action of the lipoxygenase enzyme. The term is almost always used to describe an inhibitor of the arachidonate 5-lipoxygenase enzyme, which transforms EFAs into leukotrienes.
Progesterone also known as P4 (pregn-4-ene-3,20-dione) is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. Progesterone belongs to a class of hormones called progestogens, and is the major naturally occurring human progestogen.
Progesterone was independently discovered by four research groups.
Willard Myron Allen co-discovered progesterone with his anatomy professor George Washington Corner at the University of Rochester Medical School in 1933. Allen first determined its melting point, molecular weight, and partial molecular structure. He also gave it the name Progesterone derived from Progestational Steroidal ketone.
Like other steroids, progesterone consists of four interconnected cyclic hydrocarbons. Progesterone contains ketone and oxygenated functional groups, as well as two methyl branches. Like all steroid hormones, it is hydrophobic.
Progesterone is produced in the ovaries (by the corpus luteum), the adrenal glands (near the kidney), and, during pregnancy, in the placenta. Progesterone is also stored in adipose (fat) tissue.
In humans, increasing amounts of progesterone are produced
Serotonin–norepinephrine reuptake inhibitors (SNRIs) are a class of antidepressant drugs used in the treatment of major depression and other mood disorders. They are sometimes also used to treat anxiety disorders, obsessive-compulsive disorder (OCD), attention deficit hyperactivity disorder (ADHD), chronic neuropathic pain, fibromyalgia syndrome (FMS), and for the relief of menopausal symptoms.
SNRIs act upon, and increase, the levels of two neurotransmitters in the brain known to play an important part in mood: serotonin, and norepinephrine. These can be contrasted with the more widely-used selective serotonin reuptake inhibitors (SSRIs) which act upon serotonin alone.
SNRIs are approved for treatment of the following conditions:
SNRIs are delivered orally, usually in the form of gel capsules. The drugs themselves are usually a fine crystalline powder which diffuses into the body during digestion.
Dosages fluctuated depending on the SNRI used due to varying potencies of the drug in question as well as multiple strengths for each drug.
The disease for which SNRIs are mostly indicated, Major Depressive Disorder, is thought to be mainly caused by decreased levels of serotonin and
Prostacyclin (or PGI2) is a member of the family of lipid molecules known as eicosanoids. It inhibits platelet activation and is also an effective vasodilator.
As a drug, it is also known as "epoprostenol". The terms are sometimes used interchangeably.
During the 1960s, a U.K. research team, headed by Professor John Vane, began to explore the role of prostaglandins in anaphylaxis and respiratory diseases. Working with a team from the Royal College of Surgeons, Sir John discovered that aspirin and other oral anti-inflammatory drugs work by inhibiting the synthesis of prostaglandins. This critical finding opened the door to a broader understanding of the role of prostaglandins in the body.
Sir John and a team from the Wellcome Foundation, had identified a lipid mediator they called “PG-X,” which inhibits platelet aggregation. PG-X, which later would become known as prostacyclin, is 30 times more potent than any other then-known anti-aggregatory agent.
By 1976, Sir John and fellow researchers Salvador Moncada, Ryszard Gryglewski and Stuart Bunting published the first paper on prostacyclin, in the scientific journal Nature. The collaboration produced a synthesized molecule, which was
An inhalational anaesthetic is a chemical compound possessing general anaesthetic properties that can be delivered via inhalation. They are administered by anaesthetists (a term which includes anaesthesiologists, nurse anaesthetists, and anaesthesiologist assistants) through an anaesthesia mask, laryngeal mask airway or tracheal tube connected to some type of anaesthetic vaporiser and an anaesthetic delivery system. Agents of significant contemporary clinical interest include volatile anaesthetic agents such as isoflurane, sevoflurane and desflurane, as well as certain anaesthetic gases such as nitrous oxide and xenon.
Although some of these are still used in clinical practice and in research, the following anaesthetic agents are primarily of historical interest in developed countries:
Volatile anaesthetic agents share the property of being liquid at room temperature, but evaporating easily for administration by inhalation. All of these agents share the property of being quite hydrophobic (i.e., as liquids, they are not freely miscible with water, and as gases they dissolve in oils better than in water). The ideal volatile anaesthetic agent offers smooth and reliable induction and
Tetracyclines are a group of broad-spectrum antibiotics whose general usefulness has been reduced with the onset of bacterial resistance. Despite this, they remain the treatment of choice for some specific indications.
They are so named for their four (“tetra-”) hydrocarbon rings (“-cycl-”) derivation (“-ine”). To be specific, they are defined as "a subclass of polyketides having an octahydrotetracene-2-carboxamide skeleton". They are collectively known as "derivatives of polycyclic naphthacene carboxamide".
Tetracyclines are generally used in the treatment of infections of the urinary tract and the intestines, and is used in the treatment of chlamydia, especially in patients allergic to β-lactams and macrolides; however, their use for these indications is less popular than it once was due to widespread development of resistance in the causative organisms.
Their most common current use is in the treatment of moderately severe acne and rosacea (tetracycline, oxytetracycline, doxycycline, or minocycline).
Doxycycline is also used as a prophylactic treatment for infection by Bacillus anthracis (anthrax) and is effective against Yersinia pestis, the infectious agent of bubonic plague.
Thiazide is a type of molecule and a class of diuretics often used to treat hypertension (high blood pressure) and edema (such as that caused by heart, liver, or kidney disease).
The thiazides and thiazide-like diuretics reduce the risk of death, stroke, heart attack and heart failure due to hypertension. In most countries, the thiazides are the cheapest antihypertensive drugs available.
Thiazides are often used to treat hypertension, although they are also used to treat congestive heart failure and symptomatic edema. They are the recommended first-line treatment in the US (JNC VII) guidelines for hypertension and a recommended treatment in the European (ESC/ESH) guidelines. However, the recent 2011 UK National Institute for Health and Clinical Excellence (NICE) guideline on the management of primary hypertension in adults (CG127) recommend calcium channel blockers (CCBs) as first line agents in hypertension and advise that thiazide-like diuretics should only be used first line if CCBs are not suitable or if the patient has edema or has a high risk of developing heart failure. Thiazides have also been replaced by angiotensin converting enzyme (ACE) inhibitors in Australia due to
An antiemetic is a drug that is effective against vomiting and nausea. Antiemetics are typically used to treat motion sickness and the side effects of opioid analgesics, general anaesthetics, and chemotherapy directed against cancer.
Anti-emetics are also used for morning sickness, but there is little information about the effect on the fetus, and doctors prefer not to use them unless it is strictly necessary.
Fertility medication are drugs which enhance reproductive fertility. For women, fertility medication is used to stimulate follicle development of the ovary. There are currently very few fertility medication options available for men.
Agents that enhance ovarian activity can be classified as either Gonadotropin releasing hormone, Estrogen antagonists or Gonadotropins.
Either Gonadotropin-releasing hormone (GnRH) or any Gonadotropin-releasing hormone agonist (i.e. Lupron) may be used. GnRH releases gonadotropins from the hypothalamus in the body.
Fertility medication inhibiting the effects of estrogen includes Clomiphene citrate and Aromatase inhibitors.
Clomiphene citrate is a selective estrogen receptor modulator (SERM). It is used as an ovarian stimulator by inhibiting the negative feedback of estrogen.
Although primarily a breast cancer treatment, aromatase inhibitors can also work as fertility medication, probably through a mechanism similar to clomiphene citrate.
Gonadotropins are the hormones in the body that normally stimulate the gonads (testes and ovaries). For medication, they can be extracted from urine or by genetic modification.
For example, the so called menotropins
Corticosteroids are a class of chemicals that includes steroid hormones naturally produced in the adrenal cortex of vertebrates and analogues of these hormones that are synthesized in laboratories. Corticosteroids are involved in a wide range of physiologic processes, including stress response, immune response, and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte levels, and behavior.
Some common natural hormones are corticosterone (C21H30O4), cortisone (C21H28O5, 17-hydroxy-11-dehydrocorticosterone) and aldosterone.
The corticosteroids are synthesized from cholesterol within the adrenal cortex. Most steroidogenic reactions are catalysed by enzymes of the cytochrome P450 family. They are located within the mitochondria and require adrenodoxin as a cofactor (except 21-hydroxylase and 17α-hydroxylase).
Aldosterone and corticosterone share the first part of their biosynthetic pathway. The last part is mediated either by the aldosterone synthase (for aldosterone) or by the 11β-hydroxylase (for corticosterone). These enzymes are nearly identical (they share 11β-hydroxylation and 18-hydroxylation functions), but aldosterone synthase is also able
Linear polysaccharides composed of disaccharide repeating units of glycosamine-glycans, two monosaccharide units (hexosamine and the repeating disaccharide of either hexuronate or galactose) located on the surface of cells or in the extracellular matrix contributing to adhesion, elasticity, and viscosity of extracellular substances.
A beta-lactamase inhibitor is a molecule used in conjunction with a beta-lactam antibiotic to extend its spectrum of activity.
Although beta-lactamase inhibitors have little antibiotic activity of their own, they instead inhibit the activity of beta-lactamases, a family of enzymes that break the beta-lactam ring that allows penicillin-like antibiotics to work, thereby conferring bacterial resistance.
Some bacteria can produce extended spectrum beta-lactamases, or ESBLs, making the infection more difficult to treat and conferring additional resistance to penicillins, cephalosporins, and carbapenems.
Bacteria that can produce beta-lactamases include, but are not limited to:
Carbonic anhydrase inhibitors are a class of pharmaceuticals that suppress the activity of carbonic anhydrase. Their clinical use has been established as antiglaucoma agents, diuretics, antiepileptics, in the management of mountain sickness, gastric and duodenal ulcers, neurological disorders, or osteoporosis.
Acetazolamide is an inhibitor of carbonic anhydrase. It is used for glaucoma, epilepsy (rarely), idiopathic intracranial hypertension, and altitude sickness. It can act as a mild diuretic by reducing NaCl and bicarbonate reabsorption in the proximal tubule. However, the distal segment partially compensates for the sodium loss, and the bicarbonaturia will produce a metabolic acidosis, further reducing the effect.
Methazolamide is also a carbonic anhydrase inhibitor. It has a longer elimination half-life than acetazolamide and is less associated with adverse effects to the kidney.
Dorzolamide is a sulfonamide) and topical carbonic anhydrase II inhibitor. It is indicated for the reduction of elevated intraocular pressure in patients with open-angle glaucoma or ocular hypertension and who are insufficiently responsive to beta-blockers. Inhibition of carbonic anhydrase II in the
Neuraminidase inhibitors are a class of antiviral drugs targeted at the influenza virus, which work by blocking the function of the viral neuraminidase protein, thus preventing the virus from reproducing by budding from the host cell.
Oseltamivir (Tamiflu) a prodrug, Zanamivir (Relenza), Laninamivir (Inavir), and Peramivir belong to this class. Unlike the M2 inhibitors, which work only against the influenza A, neuraminidase inhibitors act against both influenza A and influenza B.
Common side effects include nausea and vomiting.
Proteasome inhibitors are drugs that block the action of proteasomes, cellular complexes that break down proteins, like the p53 protein. Proteasome inhibitors are being studied in the treatment of cancer, especially multiple myeloma.
The 5-HT3 antagonists are a class of medications that act as receptor antagonists at the 5-HT3 receptor, a subtype of serotonin receptor found in terminals of the vagus nerve and in certain areas of the brain. With the notable exception of alosetron and cilansetron, which are used in the treatment of irritable bowel syndrome, all 5-HT3 antagonists are antiemetics, used in the prevention and treatment of nausea and vomiting. They are particularly effective in controlling the nausea and vomiting produced by cancer chemotherapy and are considered the gold standard for this purpose.
The 5-HT3 antagonists may be identified by the suffix –setron, and are classified under code A04AA of the WHO's Anatomical Therapeutic Chemical Classification System.
The history of the 5-HT3 receptor antagonists began in 1957, when J.H. Gaddum and Zuleika P. Picarelli at the University of Edinburgh proposed the existence of two serotonin receptor subtypes, the M and D receptors (thus named because their function could be blocked by morphine and Dibenzyline respectively), in a landmark paper. The 5-HT3 receptor was later found to correspond to the M receptor. In the 1970s, John Fozard proved that
A gonadotropin-releasing hormone agonist (GnRH agonist, GnRH–A) is a synthetic peptide modeled after the hypothalamic neurohormone GnRH that interacts with the gonadotropin-releasing hormone receptor to elicit its biologic response, the release of the pituitary hormones FSH and LH.
GnRH agonists are pregnancy category X drugs.
Agonists do not quickly dissociate from the GnRH receptor. As a result initially there is an increase in FSH and LH secretion (so-called "flare effect").
However after about ten days a profound hypogonadal effect (i.e. decrease in FSH and LH) is achieved through receptor downregulation by internalization of receptors. Generally this induced and reversible hypogonadism is the therapeutic goal.
GnRH agonists are synthetically modeled after the natural GnRH decapeptide with specific amino acid substitutions typically in position 6 and 10. These substitutions inhibit rapid degradation. Agonists with 2 substitutions include:
Triptorelin is an agonist with only a single substitution at position 6.
These medications can be administered intranasally, by injection, or by implant. Injectables have been formulated for daily, monthly, and quarterly use; and implants can
Adrenocorticotropic hormone (ACTH), also known as corticotropin, is a polypeptide tropic hormone produced and secreted by the anterior pituitary gland. It is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress (along with its precursor corticotropin-releasing hormone from the hypothalamus). Its principal effects are increased production and release of corticosteroids. A deficiency of ACTH is a cause of secondary adrenal insufficiency and an excess of it is a cause of Cushing’s syndrome.
ACTH is synthesized from pre-pro-opiomelanocortin (pre-POMC). The removal of the signal peptide during translation produces the 241-amino acid polypeptide POMC, which undergoes a series of post-translational modifications such as phosphorylation and glycosylation before it is proteolytically cleaved by endopeptidases to yield various polypeptide fragments with varying physiological activity. These fragments include NPP, Melanotropin Gamma (γ-MSH), Potential Peptide, Corticotropin (Adrenocorticotropic Hormone, or ACTH), Melanotropin Alpha (Melanocyte-Stimulating Hormone, or α-MSH), Corticotropin-like Intermediate Peptide (CLIP),
ALK inhibitors are potential anti-cancer drugs that act on tumours with variations of anaplastic lymphoma kinase (ALK) such as an EML4-ALK translocation.
About 7% of Non-small cell lung carcinomas (NSCLC) have EML4-ALK translocations.
Crizotinib is in clinical trials for NSCLC. with good results in phase II. FDA approved in Aug 2011.
AP26113 is at the preclinical stage.
NPM-ALK is a different variation/fusion of ALK that drives anaplastic large-cell lymphomas (ALCLs) and is the target of other ALK inhibitors.
Potassium-sparing diuretics are diuretic drugs that do not promote the secretion of potassium into the urine.
They are used as adjunctive therapy, together with other drugs, in the treatment of hypertension and management of congestive heart failure.
Potassium-sparing diuretics are generally used in combination with other diuretic drugs (e.g. loop diuretics) that would otherwise tend to lower the potassium levels to potentially dangerous low levels (hypokalemia). The combination therefore helps maintain a normal reference range for potassium.
On their own this group of drugs may raise potassium levels beyond the normal range, termed hyperkalemia, which risks potentially fatal arrhythmias.
The potassium-sparing diuretics are competitive antagonists that either compete with aldosterone for intracellular cytoplasmic receptor sites, or directly block sodium channels (specifically epithelial sodium channels (ENaC) by amiloride). The former prevents the production of proteins that are normally synthesized in reaction to aldosterone. These mediator proteins are not produced, and so stimulation of sodium-potassium exchange sites in the collection tubule does not occur. This prevents sodium
Synthetic prostaglandin analogues are molecules which are manufactured to bind to a prostaglandin receptor.
Wider use of prostaglandin analogues is limited by unwanted side effects and their abortive potential.
True synthetic prostaglandin E1 is also available pharmaceutically as alprostadil.
An antipsychotic (or neuroleptic) is a psychiatric medication primarily used to manage psychosis (including delusions or hallucinations, as well as disordered thought), particularly in schizophrenia and bipolar disorder, and is increasingly being used in the management of non-psychotic disorders (ATC code N05A). A first generation of antipsychotics, known as typical antipsychotics, was discovered in the 1950s. Most of the drugs in the second generation, known as atypical antipsychotics, have been developed more recently, although the first atypical antipsychotic, clozapine, was discovered in the 1950s and introduced clinically in the 1970s. Both generations of medication tend to block receptors in the brain's dopamine pathways, but antipsychotic drugs encompass a wide range of receptor targets.
A number of harmful and undesired (adverse) effects have been observed, including lowered life expectancy, extrapyramidal effects on motor control – including akathisia (an inability to sit still), trembling, and muscle weakness – weight gain, decrease in brain volume, enlarged breasts (gynecomastia) in men and milk discharge in men and women (galactorrhea due to hyperprolactinaemia),
A benzodiazepine /ˌbɛnzɵdaɪˈæzɨpiːn/ (sometimes colloquially "benzo"; often abbreviated "BZD") is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a diazepine ring. The first benzodiazepine, chlordiazepoxide (Librium), was discovered accidentally by Leo Sternbach in 1955, and made available in 1960 by Hoffmann–La Roche, which has also marketed diazepam (Valium) since 1963.
Benzodiazepines enhance the effect of the neurotransmitter gamma-aminobutyric acid (GABA-A), resulting in sedative, hypnotic (sleep-inducing), anxiolytic (anti-anxiety), anticonvulsant, and muscle relaxant properties; also seen in the applied pharmacology of high doses of many shorter-acting benzodiazepines are amnesic-dissociative actions. These properties make benzodiazepines useful in treating anxiety, insomnia, agitation, seizures, muscle spasms, alcohol withdrawal and as a premedication for medical or dental procedures. Benzodiazepines are categorized as either short-, intermediate- or long-acting. Short- and intermediate-acting benzodiazepines are preferred for the treatment of insomnia; longer-acting benzodiazepines are recommended for the treatment of anxiety.
Cholesterol absorption inhibitors are a class of compounds that prevents the uptake of cholesterol from the small intestine into the circulatory system.
An example is ezetimibe, previously known as "Sch-58235". Another example is Sch-48461. The "Sch" is for Schering-Plough, where these compounds were developed. Phytosterols are also cholesterol absorption inhibitors.
There are two sources of cholesterol in the upper intestine: dietary (from food) and biliary (from bile). Dietary cholesterol, in the form of lipid emulsions, combines with bile salts, to form bile salt micelles from which cholesterol can then be absorbed by the intestinal enterocyte.
Once absorbed by the enterocyte, cholesterol is reassembled into large intestinal lipoproteins called chylomicrons. These chylomicrons are then secreted into the lymphatics and circulated to the liver. These cholesterol particles are then secreted by the liver into the blood as VLDL particles, precursors to LDL.
As a class, cholesterol absorption inhibitors block the uptake of micellar cholesterol, thereby reducing the incorporation of cholesterol esters into chylomicron particles. By reducing the cholesterol content in chylomicrons and
Nucleoside analogues are a range of antiviral products used to prevent viral replication in infected cells. The most commonly used is Acyclovir, although its inclusion in this category is uncertain, as it contains only a partial nucleoside structure, as the sugar ring is replaced by an open-chain structure.
These agents can be used against hepatitis B virus, hepatitis C virus, herpes simplex, and HIV. Once they are phosphorylated, they work as antimetabolites by being similar enough to nucleotides to be incorporated into growing DNA strands; but they act as chain terminators and stop viral DNA Polymerase. They are not specific to viral DNA and also affect mitochondrial DNA. Because of this they have side effects such as bone marrow suppression.
There is a large family of nucleoside analogue reverse transcriptase inhibitors, because DNA production by reverse transcriptase is very different from normal human DNA replication, so it is possible to design nucleoside analogues that are preferentially incorporated by the former. Some nucleoside analogues, however, can function both as NRTIs and polymerase inhibitors for other viruses (e.g., hepatitis B). Less selective nucleoside
Omega 3 fatty acids (also called ω−3 fatty acids or n−3 fatty acids) are fats commonly found in marine and plant oils. They are polyunsaturated fatty acids with a double bond (C=C) starting after the third carbon atom from the end of the carbon chain. The fatty acids have two ends—the acid (COOH) end and the methyl (CH3) end. The location of the first double bond is counted from the methyl end, which is also known as the omega (ω) end or the n end.
The health effects of n-3 fatty acids supplementation are controversial. They are considered essential fatty acids, meaning that they cannot be synthesized by the human body but are vital for normal metabolism. Though mammals cannot synthesize n−3 fatty acids, they have a limited ability to form the long-chain n−3 fatty acids including eicosapentaenoic acid (EPA, 20 carbons and 5 double bonds), docosahexaenoic acid (DHA, 22 carbons and 6 double bonds) and α-linolenic acid (ALA, 18 carbons and 3 double bonds).
Common sources of n–3 fatty acids include fish oils, algal oil, squid oil, and some plant oils such as echium oil and flaxseed oil.
Supplementation does not appear to be associated with a lower risk of all-cause mortality.
A sulfone is a chemical compound containing a sulfonyl functional group attached to two carbon atoms. The central hexavalent sulfur atom is double bonded to each of two oxygen atoms and has a single bond to each of two carbon atoms, usually in two separate hydrocarbon substituents.
The general structural formula is R-S(=O)2-R' where R and R' are the organic groups. Sulfides are often the precursors to sulfones by organic oxidation through the intermediate formation of sulfoxides. For example dimethyl sulfide is oxidized to dimethyl sulfoxide and then to dimethyl sulfone.In the Ramberg-Bäcklund Reaction and the Julia olefination sulfones are converted to alkenes through the elimination of sulfur dioxide.
The industrially useful sulfone is sulfolane, a cyclic molecule with the formula (CH2)4SO2. It is typically prepared, not by oxidation of the thioether, but by addition of sulfur dioxide to 1,3-butadiene, followed by hydrogenation of the resulting sulfolene.
Sulfolane is probably the sulfone produced on the largest scale. It is used to extract valuable aromatic compounds ("BTX") from petroleum.
Some polymers containing sulfone groups have gained prominence in the field of
Sulfonylurea (UK: sulphonylurea) derivatives are a class of antidiabetic drugs that are used in the management of diabetes mellitus type 2. They act by increasing insulin release from the beta cells in the pancreas.
Some classify glimepiride as second-generation, while others classify it as third-generation.
All sulfonylureas contain a central S-phenylsulfonylurea structure (red) with a p- substituent on the phenyl ring (R) and various groups terminating the urea N′ end group (R2).
Sulfonylureas bind to an ATP-dependent K(KATP) channel on the cell membrane of pancreatic beta cells. This inhibits a tonic, hyperpolarizing efflux of potassium, thus causing the electric potential over the membrane to become more positive. This depolarization opens voltage-gated Ca channels. The rise in intracellular calcium leads to increased fusion of insulin granulae with the cell membrane, and therefore increased secretion of (pro)insulin.
There is some evidence that sulfonylureas also sensitize β-cells to glucose, that they limit glucose production in the liver, that they decrease lipolysis (breakdown and release of fatty acids by adipose tissue) and decrease clearance of insulin by the liver.
An antimetabolite is a chemical that inhibits the use of a metabolite, which is another chemical that is part of normal metabolism. Such substances are often similar in structure to the metabolite that they interfere with, such as the antifolates that interfere with the use of folic acid. The presence of antimetabolites can have toxic effects on cells, such as halting cell growth and cell division, so these compounds are used as chemotherapy for cancer.
Antimetabolites can be used in cancer treatment, as they interfere with DNA production and therefore cell division and the growth of tumors. Because cancer cells spend more time dividing than other cells, inhibiting cell division harms tumor cells more than other cells.
Anti-metabolites masquerade as a purine (azathioprine, mercaptopurine) or a pyrimidine, chemicals that become the building-blocks of DNA. They prevent these substances becoming incorporated in to DNA during the S phase (of the cell cycle), stopping normal development and division.
They also affect RNA synthesis. However, because thymidine is used in DNA but not in RNA (where uracil is used instead), inhibition of thymidine synthesis via thymidylate synthase
β2-adrenergic agonists, also known as β2-adrenergic receptor agonists, are a class of drugs used to treat asthma and other pulmonary disease states.
They act on the beta2-adrenergic receptor thereby causing smooth muscle relaxation, resulting in dilation of bronchial passages, vasodilation in muscle and liver, relaxation of uterine muscle, and release of insulin. Due to some Beta-1 agonism is also results in contraction of the heart muscle.
Beta-adrenergic receptors are coupled to the stimulatory G protein. The alpha subunit of the G protein activates adenylyl cyclase, which catalyzes the production of cyclic adenosine monophosphate (cAMP). In the lung, cAMP causes a decrease in the intracellular calcium concentration and, via activation of protein kinase A, both inactivates myosin light chain kinase and activates myosin light chain phosphorylase. In addition, beta-2 agonists open large conductance calcium-activated potassium channels and thereby tend to hyperpolarize airway smooth muscle cells. The combination of decreased intracellular calcium, increased membrane potassium conductance, and decreased myosin light chain kinase activity leads to smooth muscle relaxation and
A protein kinase inhibitor is a type of enzyme inhibitor that specifically blocks the action of one or more protein kinases. Protein kinases are enzymes that add a phosphate (PO4) group to a protein or other organic molecule, usually on the serine, threonine, or tyrosine amino acid. Hence, protein kinase inhibitors can be subdivided or characterised by the amino acids whose phosphorylation is inhibited: most kinases act on both serine and threonine, the tyrosine kinases act on tyrosine, and a number (dual-specificity kinases) act on all three. There are also protein kinases that phosphorylate other amino acids, including histidine kinases that phosphorylate histidine residues.
Phosphorylation is a necessary step in some cancers and inflammatory diseases. Inhibiting the protein kinases, and therefore the phosphorylation, can treat these diseases. Therefore, protein kinase inhibitors are used as drugs.
Kinase inhibitors such as dasatinib are often used in the treatment of cancer and inflammation. The novel kinase inhibitor PLX5568 is currently in clinical trials for treatment of polycystic kidney disease as well as pain.
Some of the kinase inhibitors used in treating cancer are
Phenothiazine is an organic compound that occurs in various antipsychotic and antihistaminic drugs. It has the formula S(C6H4)2NH. This yellow tricyclic compound is soluble in acetic acid, benzene, and ether. The compound is related to the thiazine-class of heterocyclic compounds. Derivatives of the parent compound find wide use as drugs.
The compound was originally prepared by Bernthsen in 1883 via the reaction of diphenylamine with sulfur, but more recent syntheses rely on the cyclization of 2-substituted diphenylsulfide. Some of the pharmaceutically significant derivatives of phenothiazine are not prepared directly from phenothiazine, although some of them are.
The synthetic dye methylene blue, containing the structure, was described in 1876. Phenothiazine itself was introduced by DuPont as an insecticide in 1935. It is sometimes used as an antihelminthic in livestock.
In the manufacture of monomers, Phenothiazine is used as a chemical stabilizer or inhibitor to prolong storage and shelf life of products like acryloyl chloride.
Many water soluble phenothiazine derivatives such as methylene blue, methylene green, thionine, and others are able to be electropolymerized into
Phosphate binders are a group of medications used to reduce the absorption of phosphate and taken with meals and snacks. They are typically used in patients with chronic renal failure (CRF) as they cannot get rid of the phosphates that get into their blood (i.e. the serum phosphate in chronic renal failure is typically elevated).
For patients with chronic renal failure, controlling serum phosphate is important because it is associated with bone pathology and regulated together with serum calcium by the parathyroid hormone (PTH).
These agents work by binding to phosphate in the GI tract, thereby making it unavailable to the body for absorption. Hence, these drugs are usually taken with meals to bind any phosphate that may be present in the ingested food. Phosphate binders may be simple molecular entities (such as aluminium, calcium, or lanthanum salts) that react with phosphate and form an insoluble compound. Phosphate binders, such as sevelamer, may also be polymeric structures which bind to phosphate and are then excreted.
With regard to phosphate binders, aluminium-containing compounds (such as aluminium hydroxide) are the least preferred because prolonged aluminium intake can
Antihypertensives are a class of drugs that are used to treat hypertension (high blood pressure). Antihypertensive therapy seeks to prevent the complications of high blood pressure, such as stroke and myocardial infarction. Evidence suggests that reduction of the blood pressure by 5 mmHg can decrease the risk of stroke by 34%, of ischaemic heart disease by 21%, and reduce the likelihood of dementia, heart failure, and mortality from cardiovascular disease. There are many classes of antihypertensives, which lower blood pressure by different means; among the most important and most widely used are the thiazide diuretics, the ACE inhibitors, the calcium channel blockers, the beta blockers, and the angiotensin II receptor antagonists or ARBs.
Which type of medication to use initially for hypertension has been the subject of several large studies and resulting national guidelines. The fundamental goal of treatment should be the prevention of the important endpoints of hypertension, such as heart attack, stroke and heart failure. Patient age, associated clinical conditions and end-organ damage also play a part in determining dosage and type of medication administered. The several classes
Barbiturates are drugs that act as central nervous system depressants, and can therefore produce a wide spectrum of effects, from mild sedation to total anesthesia. They are also effective as anxiolytics, hypnotics, and anticonvulsants. Barbiturates also have analgesic effects, however these effects are somewhat weak, preventing barbiturates from being used in surgery in the absence of other analgesics. They have addiction potential, both physical and psychological. Barbiturates have now largely been replaced by benzodiazepines in routine medical practice - for example, in the treatment of anxiety and insomnia – mainly because benzodiazepines are significantly less dangerous in overdose. However, barbiturates are still used in general anesthesia, for epilepsy, and assisted suicide. Barbiturates are derivatives of barbituric acid.
Barbituric acid was first synthesized December 6, 1864, by German researcher Adolf von Baeyer. This was done by condensing urea (an animal waste product) with diethyl malonate (an ester derived from the acid of apples). There are several stories about how the substance got its name. The most likely story is that Von Baeyer and his colleagues went to
A endothelin receptor antagonist (ERA) is a drug that blocks endothelin receptors.
Three main kinds of ERAs exist:
Sitaxentan, ambrisentan and bosentan are mainly used for the treatment of pulmonary arterial hypertension, while atrasentan is an experimental anti-cancer drug.
A recombinant form of the naturally occurring Interleukin-1 Receptor Antagonist that blocks the biological activity of Interleukin-1 by binding to the Interleukin-1 receptor. Clinical Use: Rheumatoid Arthritis.
A mood stabilizer is a psychiatric medication used to treat mood disorders characterized by intense and sustained mood shifts, typically bipolar disorder.
Used to treat bipolar disorder, mood stabilizers suppress swings between mania and depression. Mood-stabilizing drugs are also used in borderline personality disorder and Schizoaffective disorder.
The term "mood stabilizer" does not describe a mechanism, but rather an effect. More precise terminology is used to classify these agents.
Drugs commonly classed as mood stabilizers include:
Many agents described as "mood stabilizers" are also categorized as anticonvulsants. The term "anticonvulsant mood stabilizers" is sometimes used to describe these as a class. Although this group is also defined by effect rather than mechanism, there is at least a preliminary understanding of the mechanism of most of the anticonvulsants used in the treatment of mood disorders.
Sometimes mood stabilizers are used in combination, such as lithium with one of the anticonvulsants.
Most mood stabilizers are purely antimanic agents, meaning that they are effective at treating mania and mood cycling and shifting, but are not effective at treating
An opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract. The receptors in these organ systems mediate both the beneficial effects and the side effects of opioids.
Opioids are among the world's oldest known drugs; the use of the opium poppy for its therapeutic benefits predates recorded history. The analgesic (painkiller) effects of opioids are due to decreased perception of pain, decreased reaction to pain as well as increased pain tolerance. The side effects of opioids include sedation, respiratory depression, constipation, and a strong sense of euphoria. Opioids can cause cough suppression, which can be both an indication for opioid administration or an unintended side effect. Opioid dependence can develop with ongoing administration, leading to a withdrawal syndrome with abrupt discontinuation. Opioids are well known for their ability to produce a feeling of euphoria, motivating some to recreationally use opioids.
Although the term opiate is often used as a synonym for opioid, the term opiate is properly limited to the natural alkaloids found in the
An opioid antagonist is a receptor antagonist that acts on opioid receptors.
Naloxone and naltrexone are commonly used opioid antagonist drugs which are competitive antagonists that bind to the opioid receptors with higher affinity than agonists but do not activate the receptors. This effectively blocks the receptor, preventing the body from responding to opiates and endorphins.
Some opioid antagonists are not pure antagonists but in fact do produce some weak opioid partial agonist effects, and can produce analgesic effects when administered in high doses to opioid-naive individuals. Examples of such compounds include nalorphine and levallorphan. However the analgesic effects from these drugs are limited and tend to be accompanied by dysphoria, most likely due to action at the kappa opioid receptor. As they induce opioid withdrawal effects in people who are taking, or have recently used, opioid full agonists, these drugs are considered to be antagonists for practical purposes.
The weak partial agonist effect can be useful for some purposes, and has previously been used for purposes such as long-term maintenance of former opioid addicts using nalorphine, however it can also have
An osmotic diuretic is a type of diuretic that inhibits reabsorption of water and Na. They are pharmacologically inert substances that are given intravenously. They increase the osmolarity of blood and renal filtrate.
Two examples are mannitol and isosorbide.
In the nephron, osmotic diuretics act at the portions of the nephron that are water-permeable.
Osmotic diuretics works by expanding extracellular fluid and plasma volume, therefore increasing blood flow to the kidney. This washes out the cortical medullary gradient in the kidney. This stops the loop of Henle from concentrating urine, which usually uses the high osmotic and solute gradient to transport solutes and water.
These agents can also act at other parts of the body. For example, they can be used to reduce intracranial and intra-ocular pressure.
The renal proximal tubule is the primary site of action of osmotic diuretics.
Normally, water molecules follow Na out of the proximal tubule, resulting in Na and water reabsorption. When osmotic diuretics are introduced, they hold onto water molecules in the tubule. Since the luminal membrane is quite leaky to Na, this causes a high back leak of Na into the tubule.
Surfactants are compounds that lower the surface tension of a liquid, the interfacial tension between two liquids, or that between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.
The term surfactant/surfactants is a blend of surface active agents.
In Index Medicus and the United States National Library of Medicine, surfactant/surfactants is reserved for the meaning pulmonary surfactant. For the more general meaning, surface active agent/s is the heading.
Surfactants are usually organic compounds that are amphiphilic, meaning they contain both hydrophobic groups (their tails) and hydrophilic groups (their heads). Therefore, a surfactant contains both a water insoluble (or oil soluble) component and a water soluble component. Surfactants will diffuse in water and adsorb at interfaces between air and water or at the interface between oil and water, in the case where water is mixed with oil. The insoluble hydrophobic group may extend out of the bulk water phase, into the air or into the oil phase, while the water soluble head group remains in the water phase. This alignment of surfactants at the surface modifies the
5α-Reductase inhibitors (or 5-alpha-reductase inhibitors) are a group of drugs with antiandrogenic activity, used in the treatment of benign prostatic hyperplasia and androgenic (or androgenetic) alopecia. These drugs decrease the levels of available 5α-reductase prior to testosterone's binding with the enzyme, thus reducing levels of dihydrotestosterone that derives from such a bond.
5α-Reductase inhibitors are clinically used in the treatment of conditions that are exacerbated by dihydrotestosterone. To be specific, these indications may include:
In general, adverse drug reactions (ADRs) experienced with 5α-reductase inhibitors are dose-dependent. Common ADRs include impotence, decreased libido, decreased ejaculate volume, depression, and anxiety. Rare ADRs include breast tenderness and enlargement (gynecomastia), and allergic reaction.
The FDA has notified healthcare professionals that the Warnings and Precautions section of the labels for the 5-alpha reductase inhibitor (5-ARI) class of drugs has been revised to include new safety information about the increased risk of being diagnosed with a more serious form of prostate cancer (high-grade prostate cancer).
Amphenicols are a class of antibiotics with a phenylpropanoid structure. They function by blocking the enzyme peptidyl transferase on the 50S ribosome subunit of bacteria.
Examples of amphenicols include chloramphenicol, thiamphenicol, azidamfenicol and florfenicol. The first-in-class compound was chloramphenicol, introduced in 1949. Chloramphenicol was initially discovered as a natural product, but all amphenicols are now made by chemical synthesis.
A calcium channel blocker (CCB) is a chemical that disrupts the movement of calcium (Ca) through calcium channels.
CCB drugs devised to target neurons are used as antiepileptics. However, the most widespread clinical usage of calcium channel blockers is to decrease blood pressure in patients with hypertension. CCBs are particularly efficacious in treating elderly patients. Calcium channel blockers are also frequently used to alter heart rate, to prevent cerebral vasospasm, and to reduce chest pain caused by angina pectoris. Despite their effectiveness, CCB's often have a high mortality rate over extended periods of use, and have been known to have multiple side effects. Potential major risks however were mainly found to be associated with short-acting CCB's.
Calcium channel blockers work by blocking voltage-gated calcium channels (VGCCs) in cardiac muscle and blood vessels. This decreases intracellular calcium leading to a reduction in muscle contraction. In the heart, a decrease in calcium available for each beat results in a decrease in cardiac contractility. In blood vessels, a decrease in calcium results in less contraction of the vascular smooth muscle and therefore an
Nonsteroidal anti-inflammatory drugs, usually abbreviated to NSAIDs—but also referred to as nonsteroidal anti-inflammatory agents/analgesics (NSAIAs) or nonsteroidal anti-inflammatory medicines (NSAIMs)—are a class of drugs that provide analgesic and antipyretic (fever-reducing) effects, and, in higher doses, anti-inflammatory effects.
The term "nonsteroidal" distinguishes these drugs from steroids, which, among a broad range of other effects, have a similar eicosanoid-depressing, anti-inflammatory action. As analgesics, NSAIDs are unusual in that they are non narcotic.
The most prominent members of this group of drugs are aspirin, ibuprofen, and naproxen, all of which are available over the counter in most countries.
NSAIDs are usually indicated for the treatment of acute or chronic conditions where pain and inflammation are present. Research continues into their potential for prevention of colorectal cancer, and treatment of other conditions, such as cancer and cardiovascular disease.
NSAIDs are generally indicated for the symptomatic relief of the following conditions:
Aspirin, the only NSAID able to irreversibly inhibit COX-1, is also indicated for inhibition of platelet
Renin inhibitors are a group of pharmaceutical drugs used primarily in treatment of hypertension (high blood pressure).
These drugs inhibit the first and rate-limiting step of the renin-angiotensin-aldosterone system (RAAS). Since the 1970s, scientists have been trying to develop potent inhibitors with acceptable oral bioavailability. The process was difficult and took about three decades. The first and second generations faced problems such as poor bioavailability and lack of potency. Finally, the third generation was discovered. These compounds were nonpeptidic renin inhibitors, had acceptable oral bioavailability and were potent enough for clinical use. The first drug in this class was aliskiren, which received a marketing approval in 2007. As of January 2012, it is the only renin inhibitor on the market.
In 1896, the Finnish physiologist Robert Tigerstedt and the Swedish physician Per Bergman did an experiment on kidneys and the circulatory system in rabbits. They observed that blood pressure rose in the rabbits when extracts of the kidneys were injected into their jugular veins. They also discovered this substance responsible for higher blood pressure was produced in the renal
A serotonin reuptake inhibitor (SRI) is a type of drug that acts as a reuptake inhibitor for the neurotransmitter serotonin (5-hydroxytryptamine (5-HT)) by blocking the action of the serotonin transporter (SERT). This in turn leads to increased extracellular concentrations of serotonin and, therefore, an increase in serotonergic neurotransmission.
It is important to note that SRIs are not synonymous with selective serotonin reuptake inhibitors (SSRIs), as the latter term is usually used to describe the class of antidepressants of the same name, and because SRIs, unlike SSRIs, can either be selective or non-selective in their action. For example, cocaine, which non-selectively inhibits the reuptake of serotonin, norepinephrine, and dopamine, can be called an SRI but not an SSRI.
SRIs are used predominantly as antidepressants (e.g., SSRIs, SNRIs, and TCAs), though they are also commonly used in the treatment of other psychological conditions such as anxiety disorders and eating disorders. Less often, SRIs are also used to treat a variety of other medical conditions including obesity (e.g., sibutramine), neuropathic pain and fibromyalgia (e.g., duloxetine, milnacipran), and premature
Amino acids ( /əˈmiːnoʊ/, /əˈmaɪnoʊ/, or /ˈæmɪnoʊ/) are biologically important molecules made from amine (-NH2) and carboxylic acid (-COOH) functional groups, along with a side-chain specific to each amino acid. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen. About 500 amino acids are known which can be classified in many ways. Structurally they can be classified according to the functional groups' locations as alpha- (α-), beta- (β-), gamma- (γ-) or delta- (δ-) amino acids; other categories relate to polarity, acid/base/neutral, and side chain group type (including: aliphatic, acyclic, hydroxyl or sulphur-containing, aromatic). In the form of proteins, amino acids comprise the second largest component other than water of human muscles, cells and other tissues. Outside proteins, amino acids also perform critical biological roles including neurotransmitters, transport, and in synthesis.
Amino acids having both the amine and carboxylic acid groups attached to the first, or alpha, carbon atom have particular importance in biochemistry. They are known as 2-, alpha-, or α-amino acids (generic formula H2NCHRCOOH in most cases where R is an organic
Androgen, also called androgenic hormone or testoid, is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes the activity of the accessory male sex organs and development of male secondary sex characteristics. Androgens were first discovered in 1936. Androgens are also the original anabolic steroids and the precursor of all estrogens, the female sex hormones. The primary and most well-known androgen is testosterone, other less important androgens are dihydrotestosterone and androstenedione.
A subset of androgens, adrenal androgens, includes any of the 19-carbon steroids synthesized by the adrenal cortex, the outer portion of the adrenal gland (zonula reticularis—innermost region of the adrenal cortex), that function as weak steroids or steroid precursors, including dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEA-S), and androstenedione.
Besides testosterone, other androgens include:
During mammalian development, the gonads are at first capable of becoming either ovaries or testes. In
A local anesthetic (LA) is a drug that causes reversible local anesthesia, generally for the aim of having a local analgesic effect, that is, inducing absence of pain sensation, although other local senses are often affected as well. Also, when it is used on specific nerve pathways (nerve block), paralysis (loss of muscle power) can be achieved as well.
Clinical local anesthetics belong to one of two classes: aminoamide and aminoester local anesthetics. Synthetic local anesthetics are structurally related to cocaine. They differ from cocaine mainly in that they have no abuse potential and do not act on the sympathoadrenergic system, i.e. they do not produce hypertension or local vasoconstriction, with the exception of Ropivacaine and Mepivacaine that do produce weak vasoconstriction.
Local anesthetics vary in their pharmacological properties and they are used in various techniques of local anesthesia such as:
The local anesthetic lidocaine (lignocaine) is also used as a Class Ib antiarrhythmic drug.
All local anesthetics are membrane stabilizing drugs; they reversibly decrease the rate of depolarization and repolarization of excitable membranes (like nociceptors). Though many other
Psoralen (also called psoralene) is the parent compound in a family of natural products known as furocoumarins. It is structurally related to coumarin by the addition of a fused furan ring, and may be considered as a derivative of umbelliferone. Psoralen occurs naturally in the seeds of Psoralea corylifolia, as well as in the common Fig, celery, parsley and West Indian satinwood. It is widely used in PUVA (=Psoralen +UVA) treatment for psoriasis, eczema, vitiligo, and cutaneous T-cell lymphoma. Many furocoumarins are extremely toxic to fish, and some are indeed used in streams in Indonesia to catch fish.
An important use of psoralen is in PUVA treatment for skin problems such as psoriasis and (to a lesser extent) eczema and vitiligo. This takes advantage of the high UV absorbance of psoralen. The psoralen is applied first to sensitise the skin, then UVA light is applied to clean up the skin problem. Psoralen has also been recommended for treating alopecia. Psoralens are also used in photopheresis where they are mixed with the extracted leukocytes before UV radiation is applied.
Psoralen is a mutagen and is used for this purpose in molecular biology research. Psoralen intercalates
A thiazide-like diuretic is a sulfonamide diuretic that has similar physiological properties to a thiazide diuretic, but doesn't have the chemical properties of a thiazide, lacking the benzothiadiazine molecular structure.
Examples include chlorthalidone and metolazone.
Some, such as indapamide are considered thiazide-like diuretics, but don't necessarily have the same mechanism.
An acetylcholinesterase inhibitor (often abbreviated AChEI) or anti-cholinesterase is a chemical that inhibits the cholinesterase enzyme from breaking down acetylcholine, increasing both the level and duration of action of the neurotransmitter acetylcholine. In a total, reversible, quasi-irreversible (or pseudirreversible in some sources) and irreversible inhibitors exist.
Compounds which function as reversible competitive or noncompetitive inhibitors of cholinesterase are those most likely to have therapeutic uses. These include:
Compounds which function as quasi-irreversible inhibitors of cholinesterase are those most likely to have use as chemical weapons or pesticides. These include:
Some major effects of cholinesterase inhibitors:
Administration of reversible cholinoesterase inhibitors is contraindicated with those that have urinary retention due to obstruction.
When used in the central nervous system to alleviate neurological symptoms, such as rivastigmine in Alzheimer's disease, all cholinesterase inhibitors require doses to be increased gradually over several weeks, and this is usually referred to as the titration phase.
Antiprotozoal agents (ATC code: ATC P01) is a class of pharmaceuticals used in treatment of protozoan infection.
Protozoans have little in common with each other (for example, Entamoeba histolytica is less closely related to Naegleria fowleri than it is to Homo sapiens) and so agents effective against one pathogen may not be effective against another. However, metronidazole is selective for anaerobic organisms, and so it is effective against many (though not all) of these pathogens.
They can be grouped by mechanism or by organism.
The atypical antipsychotics (AAP) (also known as second generation antipsychotics) are a group of antipsychotic tranquilizing drugs used to treat psychiatric conditions. Some atypical antipsychotics are FDA approved for use in the treatment of schizophrenia. Some carry FDA approved indications for acute mania, bipolar depression, psychotic agitation, bipolar maintenance, and other indications. Both generations of medication tend to block receptors in the brain's dopamine pathways, but atypicals differ from typical antipsychotics in that they are less likely to cause extrapyramidal motor control disabilities in patients, which include unsteady Parkinson's disease-type movements, body rigidity and involuntary tremors. These abnormal body movements can become permanent even after medication is stopped.
During the course of treatment atypical antipsychotics are associated with the following benefits: higher rate of responders, efficiency in patients with refractory disease, lower risk of suicides, better functional capacity and an improved quality of life. However, there has been considerable debate about whether second-generation antipsychotic drugs are better than first-generation
In medicine, low-molecular-weight heparin (LMWH) is a class of medication used as an anticoagulant in diseases that feature thrombosis, as well as for prophylaxis in situations that lead to a high risk of thrombosis. Thrombosis, or thrombotic disease, is the formation of a clot within a blood vessel which interferes with the blood supply to tissues and causes problems such as deep vein thrombosis, pulmonary embolism when it is located in the veins, or heart attacks and strokes when located in the arteries.
Heparin is a naturally occurring polysaccharide that inhibits coagulation, the process that forms a thrombosis. Natural heparin consists of molecular chains of varying lengths, or molecular weights. Chains of varying molecular weights, from 5000 to over 40,000 Daltons, make up polydisperse pharmaceutical-grade heparin. LMWHs, in contrast, consist of only short chains of polysaccharide. LMWHs are defined as heparin salts having an average molecular weight of less than 8000 Da and for which at least 60% of all chains have a molecular weight less than 8000 Da. These are obtained by various methods of fractionation or depolymerisation of polymeric heparin.
Heparin derived from
A nicotinic antagonist is a type of anticholinergic drug that inhibits the action of acetylcholine (ACh) at nicotinic acetylcholine receptors. These compounds are mainly used for peripheral muscle paralysis in surgery, the classical agent of this type being tubocurarine, but some centrally acting compounds such as bupropion, mecamylamine, and 18-methoxycoronaridine block nicotinic acetylcholine receptors in the brain and have been proposed for treating drug addiction.
An antibacterial is a compound or substance that kills or slows down the growth of bacteria. The term is often used synonymously with the term antibiotic(s); today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic(s) has come to denote a broader range of antimicrobial compounds, including anti-fungal and other compounds.
The term antibiotic was first used in 1942 by Selman Waksman and his collaborators in journal articles to describe any substance produced by a microorganism that is antagonistic to the growth of other microorganisms in high dilution. This definition excluded substances that kill bacteria, but are not produced by microorganisms (such as gastric juices and hydrogen peroxide). It also excluded synthetic antibacterial compounds such as the sulfonamides. Many antibacterial compounds are relatively small molecules with a molecular weight of less than 2000 atomic mass units.
With advances in medicinal chemistry, most of today's antibacterials chemically are semisynthetic modifications of various natural compounds. These include, for example, the beta-lactam antibacterials, which include the penicillins (produced by fungi
Racetams are a class of nootropic drugs that share a pyrrolidone nucleus.
There is no generally accepted mechanism for racetams. They generally show no affinity for the most important receptors, although modulation of most important central neurotransmitters, including acetylcholine and glutamate have been reported. Although aniracetam and nebracetam show affinity for muscarinic receptors, only nefiracetam shows it at the nanomolar range. Modulation of protein synthesis and protein Kinase C could be a mechanism. Modification of membrane-located mechanisms of central signal transduction is another hypothesis.
Like ampakines, many racetams are positive allosteric modulators for the AMPA receptor. Other potent cognitive enhancers in development are also positive allosteric modulators for the AMPA receptor.
Racetams are understood to work by activating glutamate receptors that are colocalized with cholinergic receptors, thus increasing the firing of the latter. The racetams consequently increase memory capacity by nearly the same method as the acetylcholinesterase inhibitors.
Of the cognitive enhancing members of the racetam family, nootropic potency is increased when taken with
An antianginal is any drug used in the treatment of angina pectoris, a symptom of ischaemic heart disease.
Drugs used are nitrates, beta blockers, or calcium channel blockers.
Nitrates cause vasodilation of the venous capacitance vessels by stimulating the endothelium-derived relaxing factor (EDRF). Used to relieve both exertional and vasospastic angina by allowing venous pooling, reducing the pressure in the ventricles and so reducing wall tension and oxygen requirements in the heart. Short-acting nitrates are used to abort angina attacks that have occurred, while longer-acting nitrates are used in the prophylactic management of the condition.
Agents include nitroglycerin (glyceryl trinitrate) or pentaerythritol tetranitrate.isosorbide dinitrate and isosorbide mononitrate
Beta blockers are used in the prophylaxis of exertional angina by reducing the work the heart is allowed to perform below the level that would provoke an angina attack.
They cannot be used in vasospastic angina and can precipitate heart failure.
Agents include either cardioselectives such as acebutolol or metoprolol, or non-cardioselectives such as oxprenolol or sotalol.
Calcium ion (Ca) antagonists (Calcium
β-Lactam antibiotics (beta-lactam antibiotics) are a broad class of antibiotics, consisting of all antibiotic agents that contains a β-lactam nucleus in their molecular structures. This includes penicillin derivatives (penams), cephalosporins (cephems), monobactams, and carbapenems. Most β-lactam antibiotics work by inhibiting cell wall biosynthesis in the bacterial organism and are the most widely used group of antibiotics. Up until 2003, when measured by sales, more than half of all commercially available antibiotics in use were β-lactam compounds.
Bacteria often develop resistance to β-lactam antibiotics by synthesizing a β-lactamase, an enzyme that attacks the β-lactam ring. To overcome this resistance, β-lactam antibiotics are often given with β-lactamase inhibitors such as clavulanic acid.
β-Lactam antibiotics are indicated for the prophylaxis and treatment of bacterial infections caused by susceptible organisms. At first, β-lactam antibiotics were mainly active only against Gram-positive bacteria, yet the recent development of broad-spectrum β-lactam antibiotics active against various Gram-negative organisms has increased their usefulness.
Common adverse drug reactions
Mast cell stabilizers are cromone medications used to prevent or control certain allergic disorders. They block a calcium channel essential for mast cell degranulation, stabilizing the cell and thereby preventing the release of histamine and related mediators. One suspected pharmacodynamic mechanism is the blocking of IgE-regulated calcium channels. Without intracellular calcium, the histamine vesicles cannot fuse to the cell membrane and degranulate.
As inhalers they are used to treat asthma, as nasal sprays to treat hay fever (allergic rhinitis) and as eye drops for allergic conjunctivitis. Finally in oral form they are used to treat the rare condition of mastocytosis.
Mast cell stabiliser medications include:
In medicine, the term opiate describes any of the narcotic opioid alkaloids found as natural products in the opium poppy plant, Papaver somniferum.
Opiates are so named because they are constituents or derivatives of alkaloids found in opium, which is processed from the latex sap of the opium poppy. The major biologically active opiates found in opium are morphine, codeine, and thebaine. Semi-synthetic opiates such as hydrocodone, hydromorphone, oxycodone, and oxymorphone are derived from these substances. Papaverine, noscapine and approximately 24 other alkaloids are also present in opium, but have little to no effect on the human central nervous system, and are not considered to be opiates.
Opiates belong to the large biosynthetic group of benzylisoquinoline alkaloids.
The full synthesis of opiates from naphthoquinone (Gates synthesis) or from other simple organic starting materials is tedious and not economical. Thus, most of the opiate-type analgesics in use today are extracted from Papaver somniferum or semi-synthesized from thebaine.
In the traditional sense, opiate has referred to only the alkaloids in opium and the natural and semi-synthetic derivatives of opium. The term
An anticoagulant is a substance that prevents coagulation (clotting) of blood. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombotic disorders. Some anticoagulants are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis equipment.
Anticoagulants reduce blood clotting. This prevents deep vein thrombosis, pulmonary embolism, myocardial infarction and stroke.
These oral anticoagulants are derived from coumarin, which is found in many plants. A prominent member of this class is warfarin (coumadin). It takes at least 48 to 72 hours for the anticoagulant effect to develop. Where an immediate effect is required, heparin must be given concomitantly. These anticoagulants are used to treat patients with deep-vein thrombosis (DVT), pulmonary embolism (PE), atrial fibrillation (AF), and mechanical prosthetic heart valves.
Patients aged 80 years or more may be especially susceptible to bleeding complications, with a rate of 13 bleeds per 100 person-years. These oral anticoagulants are used widely as poisons for mammalian pests, especially rodents. (For details, see rodenticide and warfarin.) Depletion of vitamin
Inhibitors of dipeptidyl peptidase 4, also DPP-4 inhibitors or gliptins, are a class of oral hypoglycemics that block DPP-4. They can be used to treat diabetes mellitus type 2.
The first agent of the class - sitagliptin - was approved by the FDA in 2006.
Glucagon increases blood glucose levels, and DPP-4 inhibitors reduce glucagon and blood glucose levels. The mechanism of DPP-4 inhibitors is to increase incretin levels (GLP-1 and GIP), which inhibit glucagon release, which in turn increases insulin secretion, decreases gastric emptying, and decreases blood glucose levels.
Drugs belonging to this class are :
Berberine, the common herbal dietary supplement, too inhibits dipeptidyl peptidase-4, which at least partly explains its antihyperglycemic activity.
Long-term effects of DPP-4 inhibitors on mortality and morbidity are so far inconclusive, although adverse effects, including nasopharyngitis (the common cold), headache, nausea, hypersensitivity and skin reactions, have been observed in clinical studies. Consistent with this FDA approval of Novartis' DPP-4 inhibitor vildagliptin (Galvus®) was delayed because of skin lesions with blistering observed in nonhuman primate toxicology
Insulin is a peptide hormone, produced by beta cells of the pancreas, and is central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, skeletal muscles, and fat tissue to take up glucose from the blood. In the liver and skeletal muscles, glucose is stored as glycogen, and in adipocytes it is stored as triglycerides.
Insulin stops the use of fat as an energy source by inhibiting the release of glucagon. With the exception of the metabolic disorder diabetes mellitus and metabolic syndrome, insulin is provided within the body in a constant proportion to remove excess glucose from the blood, which otherwise would be toxic. When blood glucose levels fall below a certain level, the body begins to use stored sugar as an energy source through glycogenolysis, which breaks down the glycogen stored in the liver and muscles into glucose, which can then be utilized as an energy source. As a central metabolic control mechanism, its status is also used as a control signal to other body systems (such as amino acid uptake by body cells). In addition, it has several other anabolic effects throughout the body.
When control of insulin levels fails, diabetes
A progestin is a synthetic progestogen that has progestational effects similar to progesterone. The two most common uses of progestins are for hormonal contraception (either alone or with an estrogen), and to prevent endometrial hyperplasia from unopposed estrogen in hormone replacement therapy. Progestins are also used to treat secondary amenorrhea, dysfunctional uterine bleeding and endometriosis, and as palliative treatment of endometrial cancer, renal cell carcinoma, breast cancer, and prostate cancer. High-dose megestrol acetate is used to treat anorexia, cachexia, and AIDS-related wasting.
Progesterone (or sometimes the progestin dydrogesterone or 17α-hydroxyprogesterone caproate) is used for luteal support in IVF protocols, questionably for treatment of recurrent pregnancy loss, and for prevention of preterm birth in pregnant women with a history of at least one spontaneous preterm birth. They are also used in judicial chemical castration of sex offenders as well as a treatment options for those suffering from paraphilia.
The recognition of progesterone's ability to suppress ovulation during pregnancy spawned a search for a similar hormone that could bypass the problems
A recombinant protein which is chemically identical to or similar to endogenous interferon beta with antiviral and anti-tumor activities. Endogenous interferons beta are cytokines produced by nucleated cells (predominantly natural killer cells) upon exposure to live or inactivated virus, double-stranded RNA or bacterial products. These agents bind to specific cell-surface receptors, resulting in the transcription and translation of genes with an interferon-specific response element. The proteins so produced mediate many complex effects, including antiviral (the most important being inhibition of viral protein synthesis), antiproliferative and immune modulating effects. The recombinant therapeutic forms of interferon beta are interferon beta 1-a and interferon beta 1-b. (NCI05)
Vitamin A (or Vitamin A Retinol, retinal, and four carotenoids including beta carotene) is a vitamin that is needed by the retina of the eye in the form of a specific metabolite, the light-absorbing molecule retinal, that is necessary for both low-light (scotopic vision) and color vision. Vitamin A also functions in a very different role as an irreversibly oxidized form of retinol known as retinoic acid, which is an important hormone-like growth factor for epithelial and other cells.
In foods of animal origin, the major form of vitamin A is an ester, primarily retinyl palmitate, which is converted to retinol (chemically an alcohol) in the small intestine. The retinol form functions as a storage form of the vitamin, and can be converted to and from its visually active aldehyde form, retinal. The associated acid (retinoic acid), a metabolite that can be irreversibly synthesized from vitamin A, has only partial vitamin A activity, and does not function in the retina for the visual cycle.
All forms of vitamin A have a beta-ionone ring to which an isoprenoid chain is attached, called a retinyl group. Both structural features are essential for vitamin activity. The orange pigment of
Alkylating agent are so named because of their ability to add alkyl groups to many electronegative groups under conditions present in cells. They stop tumour growth by cross-linking guanine nucleobase in DNA double-helix strands - directly attacking DNA. This makes the strands unable to uncoil and separate. As this is necessary in DNA replication, the cells can no longer divide. These drugs act nonspecifically. Some of them require conversion into active substances in vivo (e.g. cyclophosphamide).
In the Anatomical Therapeutic Chemical Classification System, they are classified under L01A.
Cyclophosphamide is one of the most potent immunosuppressive substances. In small dosages, it is very efficient in the therapy of systemic lupus erythematosus, autoimmune hemolytic anemias, Wegener's granulomatosis and other autoimmune disease. High dosages cause pancytopenia and hemorrhagic cystitis.
Dialkylating agents can react with two different 7-N-guanine residues and if these are in different strands of DNA the result is cross-linkage of the DNA strands, which prevents uncoiling of the DNA double helix. If the two guanine residues are in the same strand the result is called limpet
Natural or synthetic Alpha-adrenergic Agonists selectively bind to and activate alpha adrenergic receptors of the sympathetic nervous system, mimicking the actions of natural sympathomimetic neurotransmitters (norepinephrine and related substances). Alpha-adrenergic Agonists can initiate physiological responses such as vasoconstriction, pupil dilation, and contraction of pilomotor muscles. (NCI04)
Alpha-glucosidase inhibitors are oral anti-diabetic drugs used for diabetes mellitus type 2 that work by preventing the digestion of carbohydrates (such as starch and table sugar). Carbohydrates are normally converted into simple sugars (monosaccharides), which can be absorbed through the intestine. Hence, alpha-glucosidase inhibitors reduce the impact of carbohydrates on blood sugar.
Examples of alpha-glucosidase inhibitors include:
Even though the drugs have a similar mechanism of action, there are subtle differences between acarbose and miglitol. Acarbose is an oligosaccharide, whereas miglitol resembles a monosaccharide. Miglitol is fairly well absorbed by the body, as opposed to acarbose. Moreover, acarbose inhibits pancreatic alpha-amylase in addition to alpha-glucosidase.
There are a large number of plants with Alpha-glucosidase inhibitor action.,
For example, research has shown the culinary mushroom Maitake (Grifola frondosa) has a hypoglycemic effect. The reason Maitake lowers blood sugar is because the mushroom naturally contains an alpha glucosidase inhibitor. Another plant attracting a lot of attention is Salacia oblonga.
Alpha-glucosidase inhibitors are used to
Antiseptics (from Greek ἀντί: anti, '"against" + σηπτικός: sēptikos, "putrefactive") are antimicrobial substances that are applied to living tissue/skin to reduce the possibility of infection, sepsis, or putrefaction. Antiseptics are generally distinguished from antibiotics by the latter's ability to be transported through the lymphatic system to destroy bacteria within the body, and from disinfectants, which destroy microorganisms found on non-living objects.
Some antiseptics are true germicides, capable of destroying microbes (bacteriocidal), while others are bacteriostatic and only prevent or inhibit their growth.
Antibacterials are antiseptics that have the proven ability to act against bacteria. Microbicides which destroy virus particles are called viricides or antivirals.
The widespread introduction of antiseptic surgical methods followed the publishing of the paper Antiseptic Principle of the Practice of Surgery in 1867 by Joseph Lister, inspired by Louis Pasteur's germ theory of putrefaction. In this paper, Lister advocated the use of carbolic acid (phenol) as a method of ensuring that any germs present were killed. Some of this work was anticipated by:
Arteriolar vasodilators are substances that preferentially dilate arterioles. When used on people with certain heart conditions, it causes a phenomenon known as the cardiac steal syndrome.
Arteriolar vasodilators include:
The cephalosporins (sg. /ˌsɛfəlɵˈspɔrɨn/) are a class of β-lactam antibiotics originally derived from the fungus Acremonium, which was previously known as "Cephalosporium".
Together with cephamycins they constitute a subgroup of β-lactam antibiotics called cephems.
Cephalosporins are indicated for the prophylaxis and treatment of infections caused by bacteria susceptible to this particular form of antibiotic. First-generation cephalosporins are active predominantly against Gram-positive bacteria, and successive generations have increased activity against Gram-negative bacteria (albeit often with reduced activity against Gram-positive organisms).
Common adverse drug reactions (ADRs) (≥ 1% of patients) associated with the cephalosporin therapy include: diarrhea, nausea, rash, electrolyte disturbances, and/or pain and inflammation at injection site. Infrequent ADRs (0.1–1% of patients) include vomiting, headache, dizziness, oral and vaginal candidiasis, pseudomembranous colitis, superinfection, eosinophilia, and/or fever.
The commonly quoted figure of 10% of patients with allergic hypersensitivity to penicillins and/or carbapenems also having cross-reactivity with cephalosporins
Echinocandins are antifungal drugs that inhibit the synthesis of glucan in the cell wall, probably via noncompetitive inhibition of the enzyme 1,3-β glucan synthase and are thus called penicillin of antifungals (a property shared with papulacandins). Beta glucans are polymers which, linked in their tens of thousands, make up cell wall membranes. Some other examples are cellulose and starches in the plant world, and glycogen and dextran in the animal world, made from alpha glucans.
It is used in candidiasis and aspergillosis.
They are fungicidal against some yeasts (most species of Candida, but not against Cryptococcus, Trichosporon and Rhodotorula), fungistatic against some molds (Aspergillus, but not Fusarium and Rhizopus), and modestly or minimally active active against dimorphic fungi (Blastomyces and Histoplasma). These have some activity against the spores of the fungus Pneumocystis carinii.
The present day clinically used echinocandins are semisynthetic pneumocandins, which are chemically lipopeptide in nature, consisting of large cyclic (hexa)peptides linked to a long chain fatty acid. Discovery of echinocandins stemmed from studies on papulacandins isolated from a strain of
Nicotinic acids are derivatives of pyridine which have a carboxy group.
Although the term niacin is sometimes used interchangeably with "nicotinic acid", it is more precise to only apply it to the 1-3 (meta) substituted form.
A xanthine oxidase inhibitor is any substance that inhibits the activity of xanthine oxidase, an enzyme involved in purine metabolism. In humans, inhibition of xanthine oxidase reduces the production of uric acid, and several medications that inhibit xanthine oxidase are indicated for treatment of hyperuricemia and related medical conditions including gout. Xanthine oxidase inhibitors are being investigated for management of reperfusion injury.
Xanthine oxidase inhibitors are of two kinds: purine analogues and others. Purine analogues include allopurinol, oxypurinol, and tisopurine. Others include febuxostat and inositols (phytic acid and myo-inositol).
In experiments, numerous natural products have been found to inhibit xanthine oxidase in vitro or in model animals (mice, rats). These include three flavonoids that occur in many different fruits and vegetables: kaempferol, myricetin, and quercetin. More generally, planar flavones and flavonols with a 7-hydroxyl group inhibit xanthine oxidase. An essential oil extracted from Cinnamomum osmophloeum inhibits xanthine oxidase in mice. The natural product propolis from selected sources inhibits xanthine oxidase in rats; the specific
Aromatase inhibitors (AIs) are a class of drugs used in the treatment of breast cancer and ovarian cancer in postmenopausal women. AIs may also be used off-label to treat or prevent gynaecomastia in men.
Aromatase is the enzyme which synthesizes estrogen. As breast and ovarian cancers require estrogen to grow, AIs are taken to either block the production of estrogen or block the action of estrogen on receptors.
There are 2 types of aromatase inhibitors (AIs) approved to treat breast cancer:
Aromatase inhibitors work by inhibiting the action of the enzyme aromatase, which converts androgens into estrogens by a process called aromatization. As breast tissue is stimulated by estrogens, decreasing their production is a way of suppressing recurrence of the breast tumor tissue. The main source of estrogen is the ovaries in premenopausal women, while in post-menopausal women most of the body's estrogen is produced in peripheral tissues (outside the CNS), and also a few CNS sites in various regions within the brain. Estrogen is produced and acts locally in these tissues, but any circulating estrogen, which exerts systemic estrogenic effects in men and women, is the result of estrogen
NMDA receptor antagonists are a class of anesthetics that work to antagonize, or inhibit the action of, the N-methyl d-aspartate receptor (NMDAR). They are used as anesthesia for animals and, less commonly, for humans; the state of anesthesia they induce is referred to as dissociative anesthesia. There is evidence that NMDA receptor antagonists can cause a certain type of neurotoxicity or brain damage referred to as Olney's Lesions in rodents, though such damage has never been observed in primates like humans.
Several synthetic opioids function additionally as NMDAR-antagonists, such as Meperidine, Methadone, Dextropropoxyphene, Tramadol and Ketobemidone.
Some NMDA receptor antagonists, including but not limited to ketamine (K), dextromethorphan (DXM), phencyclidine (PCP), and nitrous oxide (N2O) are popular as recreational drugs for their dissociative, hallucinogenic, and/or euphoriant properties. When used recreationally, they are classified as dissociative drugs.
NMDA receptor antagonists induce a state called dissociative anesthesia, marked by catalepsy, amnesia, and analgesia. Ketamine is a favored anesthetic for emergency patients with unknown medical history and in the
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as foreign, destroy it, and "remember" it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.
Vaccines can be prophylactic (example: to prevent or ameliorate the effects of a future infection by any natural or "wild" pathogen), or therapeutic (e.g. vaccines against cancer are also being investigated; see cancer vaccine).
The term vaccine derives from Edward Jenner's 1796 use of cow pox (Latin variola vaccinia, adapted from the Latin vaccīn-us, from vacca, cow), to inoculate humans, providing them protection against smallpox.
"With the exception of safe water, no other modality, not even antibiotics, has had such a major effect on mortality reduction and population growth."
Vaccines do not guarantee complete protection from a disease. Sometimes, this is because the host's
Vinca alkaloids are a set of anti-mitotic and anti-microtubule agents that were originally derived from the Periwinkle plant Catharanthus roseus.
Vinca alkaloids are used in the treatment of cancer. They are a class of cell-cycle-specific cytotoxic drugs that work by inhibiting the ability of cancer cells to divide: Acting upon tubulin, they prevent it from forming into microtubules, a necessary component for cellular division.
Vinca alkaloids are now produced synthetically and used as drugs in cancer therapy and as immunosuppressive drugs. These compounds include vinblastine, vincristine, vindesine, and vinorelbine.
An antidote is a substance which can counteract a form of poisoning. The term ultimately derives from the Greek αντιδιδοναι antididonai, "given against".
The antidotes for some particular toxins are manufactured by injecting the toxin into an animal in small doses and extracting the resulting antibodies from the host animals' blood. This results in an antivenom that can be used to counteract poison produced by certain species of snakes, spiders, and other venomous animals. A number of venoms lack a viable antivenom, and a bite or sting from an animal producing such a toxin often results in death. Some animal venoms, especially those produced by arthropods (e.g. certain spiders, scorpions, bees, etc.) are only potentially lethal when they provoke allergic reactions and induce anaphylactic shock; as such, there is no "antidote" for these venoms because it is not a form of poisoning and anaphylactic shock can be treated (e.g., by the use of epinephrine).
Some other toxins have no known antidote. For example, the poison aconitine, a highly poisonous alkaloid derived from various aconite species has no antidote, and as a result is often fatal if it enters the human body in sufficient
Cannabinoids are a class of diverse chemical compounds that activate cannabinoid receptors. These include the endocannabinoids (produced naturally in the body by humans and animals), the phytocannabinoids(found in cannabis and some other plants), and synthetic cannabinoids (produced chemically by humans). The most notable cannabinoid is the phytocannabinoid ∆-tetrahydrocannabinol (THC), the primary psychoactive compound of cannabis. However, there are known to exist numerous other cannabinoids with varied effects.
Synthetic cannabinoids encompass a variety of distinct chemical classes: the classical cannabinoids structurally related to THC, the nonclassical cannabinoids (cannabimimetics) including the aminoalkylindoles, 1,5-diarylpyrazoles, quinolines, and arylsulphonamides, as well as eicosanoids related to the endocannabinoids.
Before the 1980s, it was often speculated that cannabinoids produced their physiological and behavioral effects via nonspecific interaction with cell membranes, instead of interacting with specific membrane-bound receptors. The discovery of the first cannabinoid receptors in the 1980s helped to resolve this debate. These receptors are common in animals,
A T3 thyroid hormone normally synthesized and secreted by the thyroid gland in much smaller quantities than thyroxine (T4). Most T3 is derived from peripheral monodeiodination of T4 at the 5' position of the outer ring of the iodothyronine nucleus. The hormone finally delivered and used by the tissues is mainly T3.
Tricyclic antidepressants (TCAs) are heterocyclic chemical compounds used primarily as antidepressants. The TCAs were first discovered in the early 1950s and were subsequently introduced later in the decade; they are named after their chemical structure, which contains three rings of atoms. The tetracyclic antidepressants (TeCAs), which contain four rings of atoms, are a closely related group of antidepressant compounds.
In recent times, the TCAs have been largely replaced in clinical use in most parts of the world by newer antidepressants such as the selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), which typically have more favorable side-effects profiles, though they are still sometimes prescribed for certain indications.
The TCAs include the following agents which are predominantly serotonin and/or norepinephrine reuptake inhibitors:
The TCAs were developed amid the "explosive birth" of psychopharmacology in the early 1950s. The story begins with the synthesis of chlorpromazine in December 1950 by Rhône-Poulenc's chief chemist, Paul Charpentier, from synthetic antihistamines developed by Rhône-Poulenc in the 1940s.
A decongestant or nasal decongestant is a type of pharmaceutical drug that is used to relieve nasal congestion in the upper respiratory tract. The active ingredient in most decongestants is either pseudoephedrine or phenylephrine.
The vast majority of decongestants act via enhancing norepinephrine (noradrenaline) and epinephrine (adrenaline) or adrenergic activity by stimulating the α-adrenergic receptors. This induces vasoconstriction of the blood vessels in the nose, throat, and paranasal sinuses, which results in reduced inflammation (swelling) and mucus formation in these areas.
Decongestant nasal sprays and eye drops often contain oxymetazoline and are used for topical decongestion. Pseudoephedrine acts indirectly on the adrenergic receptor system, whereas phenylephrine and oxymetazoline are direct agonists. The effects are not limited to the nose, and these medicines may cause hypertension (high blood pressure) through vasoconstriction. But most decongestants are not pronounced stimulants due to lack of response from the other adrenoreceptors. Besides hypertension, common side-effects include sleeplessness, anxiety, dizziness, excitability, and nervousness.
Topical nasal or
Topoisomerase inhibitors are agents designed to interfere with the action of topoisomerase enzymes (topoisomerase I and II), which are enzymes that control the changes in DNA structure by catalyzing the breaking and rejoining of the phosphodiester backbone of DNA strands during the normal cell cycle.
In recent years, topoisomerases have become popular targets for cancer chemotherapy treatments. It is thought that topoisomerase inhibitors block the ligation step of the cell cycle, generating single and double stranded breaks that harm the integrity of the genome. Introduction of these breaks subsequently lead to apoptosis and cell death.
Topoisomerase inhibitors can also function as antibacterial agents. Quinolones have this function.
Topoisomerase inhibitors are often divided according to which type of enzyme it inhibits.
Numerous plant derived natural phenols (ex. EGCG, genistein, quercetin, resveratrol) possess strong topoisomerase inhibitory properties affecting both types of enzymes. They may express function of phytoalexins - compounds produced by plants to combat vermin and pests.
Use of topoisomerase inhibitors for antineoplastic treatments may lead to secondary neoplasms
Protease inhibitors (PIs) are a class of drugs used to treat or prevent infection by viruses, including HIV and Hepatitis C. PIs prevent viral replication by inhibiting the activity of proteases, e.g. HIV-1 protease, enzymes used by the viruses to cleave nascent proteins for final assembly of new virions.
Protease inhibitors have been developed or are presently undergoing testing for treating various viruses:
Given the specificity of the target of these drugs there is the risk, as in antibiotics, of the development of drug-resistant mutated viruses. To reduce this risk it is common to use several different drugs together that are each aimed at different targets.
Protease inhibitors were the second class of antiretroviral drugs developed. In all cases, patents remain in force until 2010 or beyond.
Researchers are investigating the use of protease inhibitors developed for HIV treatment as anti-protozoals for use against malaria and gastrointestinal protozoal infections:
Researchers are investigating whether protease inhibitors could possibly be used to treat cancer. For example, nelfinavir and atazanavir are able to kill tumor cells in culture (in a Petri dish). This effect has not
Loop diuretics are diuretics that act on the ascending loop of Henle in the kidney. They are primarily used in medicine to treat hypertension and edema often due to congestive heart failure or renal insufficiency. While thiazide diuretics are more effective in patients with normal kidney function, loop diuretics are more effective in patients with impaired kidney function.
Loop diuretics act on the Na-K-2Cl symporter (cotransporter) in the thick ascending limb of the loop of Henle to inhibit sodium and chloride reabsorption. This is achieved by competing for the Cl binding site. Because magnesium and calcium reabsorption in the thick ascending limb is dependent on sodium and chloride concentrations (primarily on the recycling of the potassium due to the lack of the electropositive gradient generation), loop diuretics also inhibit their reabsorption. By disrupting the reabsorption of these ions, loop diuretics prevent the urine from becoming concentrated and disrupt the generation of a hypertonic renal medulla. Without such a concentrated medulla, water has less of an osmotic driving force to leave the collecting duct system, ultimately resulting in increased urine production. Loop
Statins (or HMG-CoA reductase inhibitors) are a class of drugs used to lower cholesterol levels by inhibiting the enzyme HMG-CoA reductase, which plays a central role in the production of cholesterol in the liver. Increased cholesterol levels have been associated with cardiovascular diseases, and statins are therefore used in the prevention of these diseases. Research has found that statins are most effective for treating cardiovascular disease (secondary prevention), with questionable benefit in those without previous CVD but with elevated cholesterol levels. Statins have rare but severe adverse effects, particularly muscle damage, and some doctors believe they are overprescribed.
The best-selling statin is atorvastatin, marketed as Lipitor (manufactured by Pfizer) and Torvast. By 2003 atorvastatin became the best-selling pharmaceutical in history, with Pfizer reporting sales of US$12.4 billion in 2008. As of 2010, a number of statins are on the market: atorvastatin (Lipitor and Torvast), fluvastatin (Lescol), lovastatin (Mevacor, Altocor, Altoprev), pitavastatin (Livalo, Pitava), pravastatin (Pravachol, Selektine, Lipostat), rosuvastatin (Crestor) and simvastatin (Zocor, Lipex).
A group of antibiotics containing a macrocyclic lactone ring linked glycosidically to one or more sugar moieties. These antibiotics are produced by certain species of Streptomyces. They often inhibit protein synthesis by binding to the 50S subunits of 70S ribosomes. (MeSH)
Opioid receptors are a group of G protein-coupled receptors with opioids as ligands. The endogenous opioids are dynorphins, enkephalins, endorphins, endomorphins and nociceptin. The opioid receptors are ~40% identical to somatostatin receptors (SSTRs). Opiate receptors are distributed widely in the brain, and are found in the spinal cord and digestive tract.
By the mid-1960s, it had become apparent from pharmacologic studies that opiate drugs were likely to exert their actions at specific receptor sites, and that there were likely to be multiple such sites. Early studies had indicated that opiates appeared to accumulate in the brain. The receptors were first identified as specific molecules through the use of binding studies, in which opiates that had been labeled with radioisotopes were found to bind to brain membrane homogenates. The first such study was published in 1971, using H-levorphanol. In 1973, Candace Pert and Solomon H. Snyder published the first detailed binding study of what would turn out to be the μ opioid receptor, using H-naloxone. That study has been widely credited as the first definitive finding of an opioid receptor, although two other studies followed shortly
Substances that inhibit tyrosine kinase enzymes, involved with the transduction and processing of many extracellular and intracellular signals including cell proliferation. They have numerous applications in the prevention and treatment of cancer. (NCI)
A general anaesthetic (or anesthetic, see spelling differences) is a drug that brings about a reversible loss of consciousness. These drugs are generally administered by an anaesthesia provider to induce or maintain general anaesthesia to facilitate surgery. The biological mechanism(s) of the action of general anaesthetics are not well understood.
Drugs given to induce or maintain general anaesthesia can be either as gases or vapours (inhalational anaesthetics), or as injections (intravenous anaesthetics or even intramuscular). It is possible to deliver anaesthesia solely by inhalation or injection, but most commonly the two forms are combined, with an injection given to induce anaesthesia and a gas used to maintain it.
Inhalational anaesthetic substances are either volatile liquids or gases, and are usually delivered using an anaesthesia machine. An anaesthesia machine allows composing a mixture of oxygen, anaesthetics and ambient air, delivering it to the patient and monitoring patient and machine parameters. Liquid anaesthetics are vapourized in the machine. All of these agents share the property of being quite hydrophobic (i.e., as liquids, they are not freely miscible in
A muscle relaxant is a drug which affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therapeutic groups: neuromuscular blockers and spasmolytics. Neuromuscular blockers act by interfering with transmission at the neuromuscular end plate and have no central nervous system (CNS) activity. They are often used during surgical procedures and in intensive care and emergency medicine to cause paralysis. Spasmolytics, also known as "centrally acting" muscle relaxants, are used to alleviate musculoskeletal pain and spasms and to reduce spasticity in a variety of neurological conditions. While both neuromuscular blockers and spasmolytics are often grouped together as muscle relaxants, the term is commonly used to refer to spasmolytics only.
The earliest known use of muscle relaxant drugs dates back to the 16th century, when European explorers encountered natives of the Amazon Basin in South America using poison-tipped arrows that produced death by skeletal muscle paralysis. This poison, known today as curare, led to some of the earliest
Actinomycin D (also known generically as Actinomycin or Dactinomycin), is the most significant member of actinomycines, which are a class of polypeptide antibiotics isolated from soil bacteria of the genus Streptomyces. As one of the older chemotherapy drugs, it has been used for many years.
Actinomycin D was the first antibiotic shown to have anti-cancer activity. It was first isolated by Selman Waksman and his co-worker H. B. Woodruff in 1940. It was approved by the U.S. Food and Drug Administration (FDA) on December 10, 1964 and launched by Merck Sharp and Dohme under the trade name Cosmegen.
In cell biology, Actinomycin D is shown to have the ability to inhibit transcription. It does this by binding DNA at the transcription initiation complex and preventing elongation of RNA chain by RNA polymerase.
Actinomycin is a clear, yellow liquid administered intravenously and most commonly used in treatment of a variety of cancers, including:
Sometimes it will be combined with other drugs in Chemotherapy regimens, like the VAC regimen (with Vincristine and Cyclophosphamide) for treating rhabdomyosarcoma and Ewing's Sarcoma.
It is also used as a radiosensitizer in adjunct to
Antimalarial medications, also known as antimalarials, are designed to prevent or cure malaria. Such drugs may be used for some or all of the following:
Some antimalarial agents, particularly chloroquine and hydroxychloroquine, are also used in the treatment of rheumatoid arthritis and lupus-associated arthritis.
Current practice in treating cases of malaria is based on the concept of combination therapy, since this offers several advantages, including reduced risk of treatment failure, reduced risk of developing resistance, enhanced convenience, and reduced side-effects. Prompt parasitological confirmation by microscopy, or alternatively by rapid diagnostic tests, is recommended in all patients suspected of malaria before treatment is started. Treatment solely on the basis of clinical suspicion should only be considered when a parasitological diagnosis is not accessible.
It is practical to consider antimalarials by chemical structure since this is associated with important properties of each drug, such as mechanism of action.
Quinine has a long history stretching from Peru, and the discovery of the cinchona tree, and the potential uses of its bark, to the current day and a
A cardiac stimulant is a substance which acts as a stimulant of the heart -- for example, via positive chronotropic or inotropic action.
Examples of cardiac stimulant drugs are cocaine and methamphetamine.
Estrogens (AmE), or oestrogen (BE), are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal. The name comes from the Greek οἶστρος (oistros), literally meaning "gadfly" but figuratively sexual passion or desire, and the suffix -gen, meaning "producer of".
Estrogens are synthesized in all vertebrates as well as some insects. Their presence in both vertebrates and insects suggests that estrogenic sex hormones have an ancient evolutionary history.
Estrogens are used as part of some oral contraceptives, in estrogen replacement therapy for postmenopausal women, and in hormone replacement therapy for trans women.
Like all steroid hormones, estrogens readily diffuse across the cell membrane. Once inside the cell, they bind to and activate estrogen receptors which in turn modulate the expression of many genes. Additionally, estrogens have been shown to activate a G protein-coupled receptor, GPR30.
The three major naturally occurring estrogens in women are estrone (E1), estradiol (E2), and estriol (E3). Estradiol is the
α-blockers (alpha-blockers) or α-adrenergic-antagonists are pharmacological agents that act as receptor antagonists of α-adrenergic receptors (α-adrenoceptors).
When the term "alpha blocker" is used without further qualification, it sometimes refers to α1-blockers, and sometimes refers to agents that act at both types of receptors.
Examples of non-selective α-adrenergic blockers include:
Selective α1-adrenergic blockers include:
Selective α2-adrenergic blockers include:
The agents carvedilol and labetalol are both α- and β-blockers.
α-blockers are used in the treatment of several conditions, such as Raynaud's disease, hypertension, and scleroderma.
α-blockers can also be used to treat anxiety and panic disorders, such as generalized anxiety disorder, panic disorder or posttraumatic stress disorder (PTSD). While most commonly used to treat hypertension (usually in conjunction with diuretics when other treatments are ineffective), they are also often used to treat the symptoms of BPH (benign prostatic hyperplasia). Alpha-2 adrenergic receptor agonists, such as clonidine and guanfacine, act at noradrenergic autoreceptors to inhibit the firing of cells in the locus ceruleus,
Ketolides are antibiotics belonging to the macrolide group. Ketolides are derived from erythromycin by substituting the cladinose sugar with a keto-group and attaching a cyclic carbamate group in the lactone ring. These modifications give ketolides much broader spectrum than other macrolides. Moreover, ketolides are effective against macrolide-resistant bacteria, due to their ability to bind at two sites at the bacterial ribosome as well as having a structural modification that makes them poor substrates for efflux-pump mediated resistance. Ketolides block protein synthesis by binding to ribosomal subunits and may also inhibit the formation of newly forming ribosomes.
The only ketolide on the market at this moment is telithromycin, which is sold under the brand name of Ketek.
Other ketolides in development include cethromycin and solithromycin.
The retinoids are a class of chemical compounds that are related chemically to vitamin A. Retinoids are used in medicine, primarily due to the way they regulate epithelial cell growth.
Retinoids have many important and diverse functions throughout the body including roles in vision, regulation of cell proliferation and differentiation, growth of bone tissue, immune function, and activation of tumor suppressor genes.
Research is also being done into their ability to treat skin cancers. Currently 9-cis retinoic acid may be used topically to help treat skin lesions from Kaposi's sarcoma.
There are three generations of retinoids:
The basic structure of the hydrophobic retinoid molecule consists of a cyclic end group, a polyene side chain and a polar end group. The conjugated system formed by alternating C=C double bonds in the polyene side chain are responsible for the color of retinoids (typically yellow, orange, or red). Hence, many retinoids are chromophores. Alternation of side chains and end groups creates the various classes of retinoids.
First and Second generation retinoids are able to bind with several retinoid receptors due to the flexibility imparted by their alternating
The thiazolidinediones ( /θaɪ.əˌzoʊlɨdiːnˈdaɪ.oʊn/), also known as glitazones, are a class of medications used in the treatment of diabetes mellitus type 2. They were introduced in the late 1990s.
Thiazolidinediones or TZDs act by activating PPARs (peroxisome proliferator-activated receptors), a group of nuclear receptors with greatest specificity for PPARγ (gamma). The endogenous ligands for these receptors are free fatty acids (FFAs) and eicosanoids. When activated, the receptor binds to DNA in complex with the retinoid X receptor (RXR), another nuclear receptor, increasing transcription of a number of specific genes and decreasing transcription of others.
The activated PPAR/RXR dimer binds to peroxisome proliferator hormone response elements upstream of target genes in complex with a number of coactivators such as nuclear receptor coactivator 1 and CREB binding protein, this causes upregulation of genes (for a full list see PPARγ:
TZDs also increase the synthesis of certain proteins involved in fat and glucose metabolism, which reduces levels of certain types of lipids, and circulating free fatty acids. TZDs generally decrease triglycerides and increase high-density lipoprotein
A norepinephrine reuptake inhibitor (NRI, NERI) or adrenergic reuptake inhibitor (ARI), is a type of drug that acts as a reuptake inhibitor for the neurotransmitters norepinephrine (noradrenaline) and epinephrine (adrenaline) by blocking the action of the norepinephrine transporter (NET). This in turn leads to increased extracellular concentrations of norepinephrine and epinephrine and therefore an increase in adrenergic neurotransmission.
NRIs are commonly used in the treatment of conditions like ADHD and narcolepsy due to their psychostimulant effects and in obesity due to their appetite suppressant effects. They are also frequently used as antidepressants for the treatment of major depressive disorder. Additionally, many drugs of abuse such as cocaine and methylphenidate possess NRI activity, though it is important to mention that NRIs without combined dopamine reuptake inhibitor (DRI) properties are not significantly rewarding and hence are considered to have a negligible abuse potential. However, it is also mentionable that norepinephrine has been implicated as acting synergistically with dopamine when actions on the two neurotransmitters are combined (e.g., in the case of
An H1 antagonist is a histamine antagonist of the H1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions. Agents where the main therapeutic effect is mediated by negative modulation of histamine receptors are termed antihistamines; other agents may have antihistaminergic action but are not true antihistamines.
In common use, the term "antihistamine" refers only to H1 antagonists, also known as H1-receptor antagonists and H1-antihistamines. It has been discovered that these H1-antihistamines are actually inverse agonists at the histamine H1-receptor rather than antagonists per se.
In type I hypersensitivity allergic reactions, an allergen (a type of antigen) interacts with and cross-links surface IgE antibodies on mast cells and basophils. Once the mast cell-antibody-antigen complex is formed, a complex series of events that eventually leads to cell degranulation and the release of histamine (and other chemical mediators) from the mast cell or basophil occurs. Once released, histamine can react with local or widespread tissues through histamine receptors.
Histamine, acting on H1-receptors,
Cardiac glycosides are drugs used in the treatment of congestive heart failure and cardiac arrhythmia. These glycosides are found as secondary metabolites in several plants, but also in some animals, such as the milkweed butterflies.
Therapeutic uses of cardiac glycosides primarily involve the treatment of cardiac failure. Their utility results from an increased cardiac output by increasing the force of contraction. By increasing intracellular calcium as described below, cardiac glycosides increase calcium-induced calcium release and thus contraction.
Drugs such as ouabain and digoxin are cardiac glycosides. Digoxin from the foxglove plant is used clinically, whereas ouabain is used only experimentally due to its extremely high potency.
Normally, sodium-potassium pumps in the membrane of cells (in this case, cardiac myocytes) pump potassium ions in and sodium ions out. Cardiac glycosides inhibit this pump by stabilizing it in the E2-P transition state, so that sodium cannot be extruded: intracellular sodium concentration therefore increases. A second membrane ion exchanger, NCX, is responsible for 'pumping' calcium ions out of the cell and sodium ions in (3Na/Ca); raised
Gonadotropins (or glycoprotein hormones) are protein hormones secreted by gonadotrope cells of the anterior pituitary of vertebrates. This is a family of proteins, which include the mammalian hormones Follicle-stimulating hormone (FSH), Luteinizing hormone (LH), placental chorionic gonadotropins hCG and eCG and chorionic gonadotropin (CG), as well as at least two forms of fish gonadotropins. These hormones are central to the complex endocrine system that regulates normal growth, sexual development, and reproductive function. The hormones LH and FSH are secreted by the anterior pituitary gland, while hCG and eCG are secreted by the placenta.
Gonadotropin is sometimes abbreviated Gn. The British spelling is gonadotrophin.
The two principal gonadotropins in vertebrates are luteinizing hormone (LH) and follicle-stimulating hormone (FSH), although primates produce a third gonadotropin called chorionic gonadotropin (CG). LH and FSH are heterodimers consisting of two peptide chains, an alpha chain and a beta chain. LH and FSH share nearly identical alpha chains (about 100 amino acids long), whereas the beta chain provides specificity for receptor interactions. These subunits are heavily
Polymyxins are antibiotics, with a general structure consisting of a cyclic peptide with a long hydrophobic tail. They disrupt the structure of the bacterial cell membrane by interacting with its phospholipids. They are produced by the Gram-positive bacterium Bacillus polymyxa and are selectively toxic for Gram-negative bacteria due to their specificity for the lipopolysaccharide molecule that exists within many Gram-negative outer membranes.
Polymyxins B and E (also known as colistin) are used in the treatment of Gram-negative bacterial infections. The global problem of advancing antimicrobial resistance has led to a renewed interest in their use recently.
Polymyxin M is also known as "mattacin".
After binding to lipopolysaccharide (LPS) in the outer membrane of Gram-negative bacteria, polymyxins disrupt both the outer and inner membranes. The hydrophobic tail is important in causing membrane damage, suggesting a detergent-like mode of action.
Removal of the hydrophobic tail of polymyxin B yields polymyxin nonapeptide, which still binds to LPS but no longer kills the bacterial cell. However, it still detectably increases the permeability of the bacterial cell wall to other
A catecholamine (CA) is an organic compound that has a catechol (benzene with two hydroxyl side groups) and a side-chain amine.
A catechol is a 1,2-dihydroxybenzene group. Catecholamines derive from the amino acid tyrosine. Catecholamines are water-soluble and are 50%-bound to plasma proteins, so they circulate in the bloodstream.
In the human body, the most abundant catecholamines are epinephrine (adrenaline), norepinephrine (noradrenaline) and dopamine, all of which are produced from phenylalanine and tyrosine. Release of the hormones epinephrine and norepinephrine from the adrenal medulla of the adrenal glands is part of the fight-or-flight response.
Tyrosine is created from phenylalanine by hydroxylation by the enzyme phenylalanine hydroxylase. Tyrosine is also ingested directly from dietary protein. It is then sent to catecholamine-secreting neurons. Here, several reactions serially convert tyrosine to L-DOPA, to dopamine, to norepinephrine, and eventually to epinephrine.
Various stimulant drugs are catecholamine analogues.
Catecholamines have the distinct structure of a benzene ring with two hydroxyl groups, an intermediate ethyl chain, and a terminal amine group.
A dirty drug is an informal term used in pharmacology to describe drugs that may bind to many different molecular targets or receptors in the body, and so tend to have a wide range of effects and possibly negative side effects. Today, pharmaceutical companies try to make new drugs as selective as possible to minimise binding to antitargets and hence reduce the occurrence of side effects and risk of adverse reactions.
Examples of compounds often cited as "dirty drugs" include chlorpromazine, dextromethorphan and ibogaine, all of which bind to multiple receptors or influence multiple receptor systems. There may be instances of advantages to drugs that exhibit multi-receptor activity such as the anti-addictive drug ibogaine that acts within a broad range of neurohormonal systems where activity is also exhibited by drugs commonly associated with addiction including opioids, nicotine, and alcohol. Similarly chlorpromazine is primarily used as an antipsychotic, but its strong serotonin receptor blocking effects make it useful for treating serotoninergic crisis such as serotonin syndrome. Dextromethorphan for its part is widely used as a cough medication, but its other actions have led to
A diuretic provides a means of forced diuresis which elevates the rate of urination. There are several categories of diuretics. All diuretics increase the excretion of water from bodies, although each class does so in a distinct way.
In medicine, diuretics are used to treat heart failure, liver cirrhosis, hypertension and certain kidney diseases. Some diuretics, such as acetazolamide, help to make the urine more alkaline and are helpful in increasing excretion of substances such as aspirin in cases of overdose or poisoning. Diuretics are often abused by sufferers of eating disorders, especially bulimics, in attempts at weight loss.
The antihypertensive actions of some diuretics (thiazides and loop diuretics in particular) are independent of their diuretic effect. That is, the reduction in blood pressure is not due to decreased blood volume resulting from increased urine production, but occurs through other mechanisms and at lower doses than that required to produce diuresis. Indapamide was specifically designed with this in mind, and has a larger therapeutic window for hypertension (without pronounced diuresis) than most other diuretics.
High ceiling diuretics are diuretics that
An enzyme inhibitor is a molecule which binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides. Not all molecules that bind to enzymes are inhibitors; enzyme activators bind to enzymes and increase their enzymatic activity, while enzyme substrates bind and are converted to products in the normal catalytic cycle of the enzyme.
The binding of an inhibitor can stop a substrate from entering the enzyme's active site and/or hinder the enzyme from catalyzing its reaction. Inhibitor binding is either reversible or irreversible. Irreversible inhibitors usually react with the enzyme and change it chemically (e.g. via covalent bond formation). These inhibitors modify key amino acid residues needed for enzymatic activity. In contrast, reversible inhibitors bind non-covalently and different types of inhibition are produced depending on whether these inhibitors bind to the enzyme, the enzyme-substrate complex, or both.
Many drug molecules are enzyme inhibitors, so their discovery and improvement is an active area of research in
Vitamin B12, vitamin B12 or vitamin B-12, also called cobalamin, is a water-soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins. It is normally involved in the metabolism of every cell of the human body, especially affecting DNA synthesis and regulation, but also fatty acid synthesis and energy production. Neither fungi, plants or animals are capable of producing vitamin B12. Only bacteria and archaea have the enzymes required for its synthesis, and they therefore form its only sources in nature. The vitamin is the largest and most structurally complicated vitamin and can be produced industrially only through bacterial fermentation-synthesis.
Vitamin B12 consists of a class of chemically related compounds (vitamers), all of which have vitamin activity. It contains the biochemically rare element cobalt. Biosynthesis of the basic structure of the vitamin is accomplished only by bacteria (which usually produce hydroxocobalamin), but conversion between different forms of the vitamin can be accomplished in the human body. A common semi-synthetic form of the vitamin, cyanocobalamin,
Vitamin D is a group of fat-soluble secosteroids. In humans, vitamin D is unique because it can be ingested as cholecalciferol (vitamin D3) or ergocalciferol (vitamin D2) and because the body can also synthesize it (from cholesterol) when sun exposure is adequate (hence its nickname, the "sunshine vitamin").
Although vitamin D is commonly called a vitamin, it is not actually an essential dietary vitamin in the strict sense, as it can be synthesized in adequate amounts by all mammals from sunlight. An organic chemical compound (or related set of compounds) is only scientifically called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from their diet. However, as with other compounds commonly called vitamins, vitamin D was discovered in an effort to find the dietary substance that was lacking in a disease, namely, rickets, the childhood form of osteomalacia. Additionally, like other compounds called vitamins, in the developed world vitamin D is added to staple foods, such as milk, to avoid disease due to deficiency.
Measures of serum levels reflect endogenous synthesis from exposure to sunlight as well as intake from the diet, and
An anti-mineralocorticoid, or an aldosterone antagonist, refers to a diuretic drug which antagonizes the action of aldosterone at mineralocorticoid receptors. This group of drugs is often used as adjunctive therapy, in combination with other drugs, for the management of chronic heart failure. Spironolactone, the first member of the class, is also used in the management of hyperaldosteronism (including Conn's syndrome) and female hirsutism.
Aldosterone antagonists are, as the name suggests, receptor antagonists at the mineralocorticoid receptor. Antagonism of these receptors inhibits sodium resorption in the collecting duct of the nephron in the kidneys. This interferes with sodium/potassium exchange, reducing urinary potassium excretion and weakly increasing water excretion (diuresis).
In congestive heart failure, they are used in addition to other drugs for additive diuretic effect, which reduces edema and the cardiac workload.
Members of this class in clinical use include:
Aminoglycoside antibiotics are a type of antibiotic that work against many types of bacteria and includes streptomycin, gentamicin, and neomycin. Aminoglycosides are used to treat bacterial infections.
This article includes text from the U.S. National Cancer Institute's public domain Dictionary of Cancer Terms
An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. An example of an anticholinergic is dicycloverine, and the classic example is atropine. Anticholinergics are administered to reduce the effects mediated by acetylcholine on acetylcholine receptors in neurons through competitive inhibition. Therefore, their effects are reversible.
Anticholinergics are a class of medications that inhibit parasympathetic nerve impulses by selectively blocking the binding of the neurotransmitter acetylcholine to its receptor in nerve cells. The nerve fibers of the parasympathetic system are responsible for the involuntary movements of smooth muscles present in the gastrointestinal tract, urinary tract, lungs, etc. Anticholinergics are divided into three categories in accordance with their specific targets in the central and/or peripheral nervous system: antimuscarinic agents, ganglionic blockers, and neuromuscular blockers.
Anticholinergics are classified according to the receptors that are affected:
Examples of anticholinergics:
Physostigmine is one of only a few drugs that can be used as an antidote for
An antidepressant is a psychiatric medication used to alleviate mood disorders, such as major depression and dysthymia and anxiety disorders such as social anxiety disorder. According to Gelder, Mayou &*Geddes (2005) people with a depressive illness will experience a therapeutic effect to their mood; however, this will not be experienced in healthy individuals. Drugs including the monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs), tetracyclic antidepressants (TeCAs), selective serotonin reuptake inhibitors (SSRIs), and serotonin-norepinephrine reuptake inhibitors (SNRIs) are most commonly associated with the term. These medications are among those most commonly prescribed by psychiatrists and other physicians, and their effectiveness and adverse effects are the subject of many studies and competing claims.
Most typical antidepressants have a delayed onset of action (2–6 weeks) and are usually administered for anywhere from months to years. Despite the name, antidepressants are often used to treat other conditions, such as anxiety disorders, obsessive compulsive disorder, eating disorders, chronic pain, and some hormone-mediated disorders such as dysmenorrhea.
Benzothiazole is an aromatic heterocyclic compound with the chemical formula C7H5NS. It is colorless, slightly viscous liquid. Although the parent compound, benzothiazole is not widely used, many of its derivatives are found in commercial products or in nature. A derivative of benzothiazole is the light-emitting component of luciferin, found in fireflies.
Benzothiazoles consist of a 5-membered 1,3-thiazole ring fused to a benzene ring. The nine atoms of the bicycle and the attached substituents are coplanar.
Benzothiazole are prepared by treatment of 2-aminobenzenethiol with acid chlorides:
This heterocyclic scaffold is readily substituted at the unique methyne centre in the thiazole ring. Its a thermally stable electron-withdrawing moiety with numerous applications in dyes such as thioflavin. Some drugs contain this group, an example being riluzole. The heterocycle is found in nature. Accelerators for the vulcanization of rubber are based on 2-mercaptobenzothiazole. This ring is a potential component in nonlinear optics (NLO).
Beta-adrenergic agonists are adrenergic agonists which act upon the beta receptors. In general, pure beta-adrenergic agonists have the opposite function of beta blockers.
β1 agonists: stimulates adenylyl cyclase activity; opening of calcium channel. (cardiac stimulants; used to treat cardiogenic shock, acute heart failure, bradyarrhythmias). Selected examples are:
β2 agonists: stimulates adenylyl cyclase activity; closing of calcium channel (smooth muscle relaxants; used to treat asthma and COPD). Selected examples are:
The following agents are also listed as agonists by MeSH.
Bile acids are steroid acids found predominantly in the bile of mammals. Bile salts are bile acids compounded with a cation, usually sodium. In humans, the salts of taurocholic acid and glycocholic acid (derivatives of cholic acid) represent approximately eighty percent of all bile salts. Bile acids, glycine and taurine conjugates, and 7-alpha-dehydroxylated derivatives (deoxycholic acid and lithocholic acid) are all found in human intestinal bile. An increase in bile flow is exhibited with an increased secretion of bile acids. The main function of bile acid is to facilitate the formation of micelles, which promotes processing of dietary fat.
In humans, bile acid synthesis begins when liver cells synthesize the two primary bile acids, cholic acid and chenodeoxycholic acid, via the cytochrome P450-mediated oxidation of cholesterol. Approximately 600 mg of bile salts are synthesized daily to replace bile acids lost in the feces. In humans, the rate-limiting step is the addition of a hydroxyl group on position 7 of the steroid nucleus by the enzyme cholesterol 7 alpha-hydroxylase. This enzyme is down-regulated by cholic acid and up-regulated by cholesterol.
When these two bile acids
Bismuth ( /ˈbɪzməθ/ BIZ-məth) is a chemical element with symbol Bi and atomic number 83. Bismuth, a pentavalent poor metal, chemically resembles arsenic and antimony. Elemental bismuth may occur naturally, although its sulfide and oxide form important commercial ores. The free element is 86% as dense as lead. It is a brittle metal with a silvery white color when freshly produced, but is often seen in air with a pink tinge owing to surface oxidation. Bismuth is the most naturally diamagnetic and has one of the lowest values of thermal conductivity among metals.
Bismuth metal has been known from ancient times, although until the 18th century it was often confused with lead and tin, as all three metals have similar physical properties. The etymology is uncertain, but possibly comes from Arabic bi ismid, meaning having the properties of antimony or German words weisse masse or wismuth ("white mass"), translated in the mid sixteenth century to New Latin bisemutum.
Bismuth has long been considered as the highest-atomic-mass element that is stable. However, it is slightly radioactive: its only primordial isotope bismuth-209 alpha decays with a half life more than a billion times the
Calcitonin (also known as thyrocalcitonin) is a 32-amino acid linear polypeptide hormone that is produced in humans primarily by the parafollicular cells (also known as C-cells) of the thyroid, and in many other animals in the ultimobranchial body. It acts to reduce blood calcium (Ca), opposing the effects of parathyroid hormone (PTH). Calcitonin has been found in fish, reptiles, birds, and mammals. Its importance in humans has not been as well established as its importance in other animals, as its function is usually not significant in the regulation of normal calcium homeostasis. It belongs to calcitonin-like protein family.
Calcitonin is formed by the proteolytic cleavage of a larger prepropeptide, which is the product of the CALC1 gene (CALCA). The CALC1 gene belongs to a superfamily of related protein hormone precursors including islet amyloid precursor protein, calcitonin gene-related peptide, and the precursor of adrenomedullin.
Secretion of calcitonin is stimulated by:
The hormone participates in calcium (Ca) and phosphorus metabolism. In many ways, calcitonin counteracts parathyroid hormone (PTH).
More specifically, calcitonin lowers blood Ca levels in three ways:
An Endoglycosidase is an enzyme that releases oligosaccharides from glycoproteins or glycolipids. Or it merely cleaves polysaccharide chains between residues that are not the terminal residue, although releasing oligosaccharides from conjugated protein and lipid molecules is more common.
It breaks the glycosidic bonds between two sugar monomer in the polymer. It is different from exoglycosidase that it does not do so at the terminal residue. Hence, it is used to release long carbohydrates from conjugated molecules. If an exoglycosidase were used, every monomer in the polymer would have to be removed, one by one from the chain, taking a long time. An endoglycosidase cleaves, giving a polymeric product.
The mechanism is an enzymatic hydrolysis that requires two critical molecules; a proton donor (most likely an acid) and a nucleophile(most likely a base).(1) The Endoglycosidases mechanism has two forms; an acid catalyzed protonation of the glycosidic oxygen yielding stereochemical retention at the anomeric carbon or an acid catalyzed protonation of the glycosidic oxygen with a concomitant attack of a water molecule activated by the
Erythropoiesis-stimulating agent, commonly abbreviated ESA, an agent similar to the cytokine (erythropoetin) that stimulates red blood cell production (erythropoeisis). ESAs, structurally and biologically, are similar to naturally occurring protein erythropoietin.
Physicians prescribe ESAs to maintain hemoglobin at the lowest level that both minimizes transfusions and best meets individual patient needs. Medical speciality professional organizations do not recommend the use of ESAs to chronic kidney disease patients who do not have hemoglobin levels greater than 10 g/dL and do not have anemia symptoms.
The gamma or immune IFNs are produced by T lymphocytes in response to mitogens or to antigens to which they are sensitized. They are acid-labile and serologically distinct from alpha- and beta-IFNs. (from OMIM 147570)
A pyrethroid is an organic compound similar to the natural pyrethrins produced by the flowers of pyrethrums (Chrysanthemum cinerariaefolium and C. coccineum). Pyrethroids now constitute the majority of commercial household insecticides. In the concentrations used in such products, they may also have insect repellent properties and are generally harmless to human beings in low doses but can harm sensitive individuals. They are usually broken apart by sunlight and the atmosphere in one or two days, and do not significantly affect groundwater quality. Pyrethroids are however toxic to aquatic organisms.
Pyrethroids are popular for insecticide because exoskeletons of insects are sufficiently porous to pyrethroids. They are axonic poisons and cause paralysis of an organism by keeping the sodium channels open in the neuronal membranes. The sodium channel consists of a membrane protein with a hydrophilic interior; this interior is effectively a tiny hole that is shaped exactly right to strip away the partially charged water molecules from a sodium ion and create a favorable way for sodium ions to pass through the membrane, enter the axon, and propagate an action potential. When the toxin
Reversible inhibitors of monoamine oxidase A (RIMAs) are a class of drugs which selectively and reversibly inhibit the enzyme monoamine oxidase A (MAO-A). They are used clinically in the treatment of depression and dysthymia, though they have not gained widespread market share due to limited efficacy relative to other antidepressants. Because of their reversibility and selectivity, RIMAs are safer than the older monoamine oxidase inhibitors (MAOIs) like phenelzine and tranylcypromine.
RIMAs are displaced from MAO-A in the presence of tyramine, rather than inhibiting its breakdown in the liver as general MAOIs do. Additionally, MAO-B remains free and continues to metabolize tyramine in the stomach, although this is less significant than the liver action. Thus, RIMAs are unlikely to elicit tyramine-mediated hypertensive crisis, and a special diet does not need to be so strictly adhered to, although eating excessively large amounts of tyramine-containing foods is still not advisable.
While safer than general MAOIs, RIMAs still have highly dangerous and sometimes fatal interactions with many common drugs; in particular, they can cause serotonin syndrome or hypertensive crisis when
Selective serotonin re-uptake inhibitors or serotonin-specific reuptake inhibitor (SSRIs) are a class of compounds typically used as antidepressants in the treatment of depression, anxiety disorders, and some personality disorders.
SSRIs are believed to increase the extracellular level of the neurotransmitter serotonin by inhibiting its reuptake into the presynaptic cell, increasing the level of serotonin in the synaptic cleft available to bind to the postsynaptic receptor. They have varying degrees of selectivity for the other monoamine transporters, with pure SSRIs having only weak affinity for the noradrenaline and dopamine transporter.
The efficacy of SSRIs in mild or moderate cases has been disputed. A 2010 meta-analysis states that "The magnitude of benefit of antidepressant medication compared with placebo ... may be minimal or nonexistent, on average, in patients with mild or moderate symptoms. For patients with very severe depression, the benefit of medications over placebo is substantial." This analysis discarded a great majority of FDA-approved antidepressant studies, including those that used placebo washout periods typically used as controls.
SSRIs are the first class
A serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI), or triple reuptake inhibitor (TRI), is a drug/ligand that simultaneously acts as a reuptake inhibitor for the monoamine neurotransmitters, serotonin (5-HT), norepinephrine (noradrenaline, NA) and dopamine (DA), by blocking the action of the serotonin transporter (SERT), norepinephrine transporter (NET), and dopamine transporter (DAT), respectively. This, in turn, leads to increased extracellular concentrations of these neurotransmitters and, therefore, an increase in serotonergic, noradrenergic or adrenergic, and dopaminergic neurotransmission. In this sense, to a degree, there is omnipresence in what these compounds do. This group of drugs/ligands are believed to work in much the same way as the nonselective monoamine releasers (E.G. 4-FA, PBA, and PAL-287), albeit through a differing mechanism of activity.
The exact chemical signature depends on the specific compound under consideration. In addition, there is the case of the nonselective MAOIs, including tranylcypromine and phenelzine, to consider. These also elevate the extracellular concentration of (and the amount of synaptic signaling of) monoaminergic
Vitamin K antagonists (VKA) is a group of drugs that reduce blood clotting by inhibiting the recycling of vitamin K epoxide back to the active reduced form of vitamin K. These drugs reduce the action of vitamin K by depleting the active form of the vitamin. The term "vitamin K antagonist" is a misnomer, as the drugs don't directly antagonise the action of vitamin K, but rather the recycling of vitamin K.
On the basis of its mechanism of action, the action of this class of anticoagulants in all cases may thus be reversed by administering vitamin K for the duration of the anticoagulant's residence in the body, and the daily dose needed for reversal is the same for all drugs in the class. However, in the case of the second generation "super warfarins" intended to kill warfarin resistant rodents, the time of vitamin K administration may need to be prolonged to months, in order to combat the long residence time of the poison.
The vitamin K antagonists can cause birth defects (teratogens).
Coumarins (more accurately 4-hydroxycoumarins) are the most commonly used VKA (they are a subset of VKAs), and sometimes the terms are loosely used synonymously (though this also is not quite