A drug's mechanism of action is the biological or chemical mechanism by which the drug acts. For example, "Corticosteroid hormone receptor agonist".
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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:
Drugs with this mechanism of action:Bisoprolol/Hydrochlorothiazide
Adrenergic beta-receptor blockaders (beta-blockers) are "drugs that bind to but do not activate beta-adrenergic receptors thereby blocking the actions of beta-adrenergic agonists. Adrenergic beta-antagonists are used for treatment of hypertension, cardiac arrhythmias, angina pectoris, glaucoma, migraine headaches, and anxiety". Beta-blockers vary within the class regarding their properties. Beta-blockers that have low intrinsic sympathomimetic activity (ISA), low membrane stabilizing activity, high beta 1-selectivity, and high lipophilicity may be more effective.
Generically available beta-blockers, which subclassify based on selective aspects of their action, include:
They further divide by frequency of dosing, cost, and other factors.
Even among drugs selective for the beta-1 adrenergic receptor, drugs vary in their selectivity. Generic beta-blockers with selectivity for the beta-1 adrenergic receptor:
Non-selective drugs include propranolol, timolol, nadolol, pindolol, penbutolol, and carteolol.
Generic beta-blockers with intrinsic sympathomimetic activity (less resting bradycardia and lipid changes):
Generic beta-blockers with alpha blocking activity
Selective estrogen receptor modulators (SERMs) are a class of compounds that act on the estrogen receptor. A characteristic that distinguishes these substances from pure receptor agonists and antagonists is that their action is different in various tissues, thereby granting the possibility to selectively inhibit or stimulate estrogen-like action in various tissues. Phytoserms are SERMs from a botanical source.
SERMs are used dependent on their pattern of action in various tissues:
Other members include afimoxifene, arzoxifene, and bazedoxifene.
Some SERMs may be good replacements for hormone replacement therapy (HRT), which had been commonly used to treat menopause symptoms until the publication of wide scale studies showing that HRT slightly increases the risk of breast cancer and thrombosis. Some of the above agents still have significant side-effects that contraindicate widespread use.
Estrogenic compounds span a spectrum of activity ranging from:
The mechanism of mixed agonism/antagonism may differ depending on the chemical structure of the SERM, but, for at least for some SERMs, it appears to be related to (1) the ratio of co-activator to co-repressor proteins in different
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
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
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)
A dopamine agonist is a compound that activates dopamine receptors in the absence of dopamine. Dopamine agonists activate signaling pathways through the dopamine receptor and trimeric G-proteins, ultimately leading to changes in gene transcription.
Some medical drugs act as dopamine agonists and can treat hypodopaminergic (low dopamine) conditions; they are typically used for treating Parkinson's disease and certain pituitary tumors (prolactinoma), and may be useful for restless legs syndrome (RLS). Both Requip (Ropinirole) and Mirapex (Pramipexole) are FDA-approved for the treatment of RLS. There is also an ongoing clinical trial to test the effectiveness of the dopamine agonist Requip (ropinirole) in reversing the symptoms of SSRI-induced sexual dysfunction and Post-SSRI sexual dysfunction (PSSD). Additionally, a systematic review and meta-analysis concluded that prophylactic treatment with cabergoline reduces the incidence, but not the severity, of ovarian hyperstimulation syndrome (OHSS), without compromising pregnancy outcomes, in females undergoing stimulated cycles of in vitro fertilization (IVF). Agonists of dopaminergic receptors can also be used as an antidote for
Drugs with this mechanism of action:Hydrocodone/ibuprofen
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
Drugs with this mechanism of action:Chlorcyclizine/Pseudoephedrine
An adrenergic alpha-agonist (or alpha-adrenergic agonist) is a drug that selectively stimulates alpha adrenergic receptors. The alpha-adrenergic receptor has two subclasses α1 and α2.
Although complete selectivity between receptor agonism is rarely achieved, some agents have partial selectivity.
α1 agonists: stimulates phospholipase C activity. (vasoconstriction and mydriasis; used as vasopressors, nasal decongestants and eye exams). Selected examples are:
α2 agonists: inhibits adenylyl cyclase activity. (reduce brainstem vasomotor center-mediated CNS activation; used as antihypertensives, sedatives & treatment of opiate dependence and alcohol withdrawal symptoms). Selected examples are:
The following agents are also listed as agonists by MeSH.
Alpha-adrenergic agonists are used in the treatment of glaucoma by decreasing the production of aqueous fluid by the ciliary bodies of the eye and also by increasing uveoscleral outflow.
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.
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
A protein synthesis inhibitor is a substance that stops or slows the growth or proliferation of cells by disrupting the processes that lead directly to the generation of new proteins.
While a broad interpretation of this definition could be used to describe nearly any antibiotic, in practice, it usually refers to substances that act at the ribosome level (either the ribosome itself or the translation factor), taking advantages of the major differences between prokaryotic and eukaryotic ribosome structures.
Toxins such as ricin also function via protein synthesis inhibition. Ricin acts at the eukaryotic 60S.
In general, protein synthesis inhibitors work at different stages of prokaryotic mRNA translation into proteins, like initiation, elongation (including aminoacyl tRNA entry, proofreading, peptidyl transfer, and ribosomal translocation) and termination:
The following antibiotics bind to the 30S subunit of the ribosome:
The following antibiotics bind to the 50S ribosomal subunit:
Drugs with this mechanism of action:Indocyanine green
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber.
Both dyes and pigments appear to be colored because they absorb some wavelengths of light more than others. In contrast with a dye, a pigment generally is insoluble, and has no affinity for the substrate. Some dyes can be precipitated with an inert salt to produce a lake pigment, and based on the salt used they could be aluminum lake, calcium lake or barium lake pigments.
Dyed flax fibers have been found in the Republic of Georgia dated back in a prehistoric cave to 36,000 BP. Archaeological evidence shows that, particularly in India and Phoenicia, dyeing has been widely carried out for over 5,000 years. The dyes were obtained from animal, vegetable or mineral origin, with no or very little processing. By far the greatest source of dyes has been from the plant kingdom, notably roots, berries, bark, leaves and wood, but only a few have ever been used on a commercial scale.
The majority of natural dyes are from plant sources – roots, berries, bark, leaves, and wood,
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
Any agents that inhibit mTOR (FK506 binding protein 12-rapamycin associated protein 1), one of the protein kinases mediate cellular responses to stresses such as DNA damage and nutrient deprivation. mTOR acts as the target for the cell-cycle arrest and immunosuppressive effects of the FKBP12-rapamycin complex.
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
Drugs with this mechanism of action:Aliskiren/Valsartan
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 dopamine reuptake inhibitor (DRI, DARI) is a type of drug that acts as a reuptake inhibitor for the neurotransmitter dopamine by blocking the action of the dopamine transporter (DAT). This in turn leads to increased extracellular concentrations of dopamine and therefore an increase in dopaminergic neurotransmission.
DRIs are frequently used in the treatment of conditions like ADHD and narcolepsy on account of their psychostimulant effects and in the treatment of obesity due to their appetite suppressant properties. They have also been used as antidepressants in the treatment of mood disorders, but their use for this indication has been limited on account of their abuse potential and restricted nature. Additionally, many DRIs such as cocaine are drugs of abuse due to the rewarding effects evoked by elevated synaptic concentrations of dopamine in the brain.
Due to their strong rewarding and reinforcing properties, DRIs are notorious for their high abuse potential and liability to cause cravings, addiction, and dependence. DRIs such as cocaine and methylphenidate and combination releasing agents such as amphetamine, methamphetamine, and MDMA ("ecstasy") are widely used
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
Drugs with this mechanism of action:Lidocaine/Epinephrine
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.
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
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
Angiotensin II receptor antagonists, also known as angiotensin receptor blockers (ARBs), AT1-receptor antagonists or sartans, are a group of pharmaceuticals which modulate the renin-angiotensin-aldosterone system. Their main uses are in the treatment of hypertension (high blood pressure), diabetic nephropathy (kidney damage due to diabetes) and congestive heart failure.
Angiotensin II receptor blockers are primarily used for the treatment of hypertension where the patient is intolerant of ACE inhibitor therapy. They do not inhibit the breakdown of bradykinin or other kinins, and are thus only rarely associated with the persistent dry cough and/or angioedema that limit ACE inhibitor therapy. More recently, they have been used for the treatment of heart failure in patients intolerant of ACE inhibitor therapy, particularly candesartan. Irbesartan and losartan have trial data showing benefit in hypertensive patients with type II diabetes, and may delay the progression of diabetic nephropathy. Candesartan is used experimentally in preventive treatment of migraine. Lisinopril has been found less often effective than candesartan at preventing migraine.
The angiotensin II receptor blockers
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
Drugs with this mechanism of action:Lopinavir/ritonavir
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
A cholinesterase inhibitor or anticholinesterase is a chemical that inhibits a cholinesterase enzyme from breaking down acetylcholine, so increasing both the level and duration of action of the neurotransmitter acetylcholine.
Anticholinesterases occur naturally as venoms and poison, are used as weapons in the form of nerve agent, and are used medicinally to treat diseases such as myasthenia gravis and Alzheimer's disease, and as an antidote to anticholinergic poisoning. In myasthenia gravis, they are used to increase neuromuscular transmission.
Compounds which function as reversible competitive or noncompetitive inhibitor of cholinesterase are those most likely to have therapeutic uses. These include:
Compounds which function as quasi-irreversible inhibitor of cholinesterase are those most likely to have use as chemical weapon or pesticide. These include:
Some major effects of anticholinesterase:
Actions on the autonomic nervous system, that is parasympathetic nervous system will cause bradycardia, hypotension, hypersecretion, bronchoconstriction, GIT hypermotility, and decrease intraocular pressure.
Actions on the neuromuscular junction will result in prolonged muscle
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.
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
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
Drugs with this mechanism of action:Acyclovir/Hydrocortisone
An agent that inhibits the function of DNA polymerase, an enzyme that is essential for DNA replication and repair, and subsequently for cell division. By inhibiting DNA polymerase, a DNA polymerase inhibitor induces cell death, especially in the rapidly proliferating cell populations found in tumors. (NCI04)
An aromatic L-amino acid decarboxylase inhibitor (synonyms: DOPA decarboxylase inhibitor, DDCI and AAADI) is a drug which inhibits the synthesis of dopamine by the enzyme aromatic L-amino acid decarboxylase (AAAD, or DOPA decarboxylase, DDC).
Peripheral DDCIs incapable of crossing the protective blood-brain-barrier (BBB) are used in augmentation of L-DOPA (Levodopa) in the treatment of Parkinson's disease (PD) to block the peripheral conversion of L-DOPA into dopamine for the purpose of reducing adverse side effects. Combined l-dopa and DDCI therapy does not inherently decrease peripheral cardiovascular side effects of l-dopa administration; however, combined therapy potentiates the central effects of l-dopa by decreasing the dose-dependency 4-5 fold, therein allowing for effective Parkinson's Disease treatment without cardiovascular risk associated with high peripheral dopamine.
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
A histamine antagonist (commonly called an antihistamine) is a pharmaceutical drug that inhibits the action of histamine by blocking it from attaching to histamine receptors; or it may inhibit the enzymatic activity of histidine decarboxylase, catalyzing the transformation of histidine into histamine (atypical antihistaminics).
Antihistamines are commonly used for the relief of allergies caused by intolerance of proteins.
Histamines produce increased vascular permeability, causing fluid to escape from capillaries into tissues, which leads to the classic symptoms of an allergic reaction — a runny nose and watery eyes. Histamine also promotes angiogenesis.
Antihistamines suppress the histamine-induced wheal response (swelling) and flare response (vasodilation) by blocking the binding of histamine to its receptors on nerves, vascular smooth muscle, glandular cells, endothelium, and mast cells. They exert a competitive antagonism to histamines.
Itching and sneezing are suppressed by antihistamine blocking of H1-receptors on nasal sensory nerves.
In common use, the term antihistamine refers only to H1 antagonists, also known as H1 antihistamines. It has been discovered that these
Drugs with this mechanism of action:Piperacillin/tazobactam
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:
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,
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
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.
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).
Integrase inhibitors are a class of antiretroviral drug designed to block the action of integrase, a viral enzyme that inserts the viral genome into the DNA of the host cell. Since integration is a vital step in retroviral replication, blocking it can halt further spread of the virus. Integrase inhibitors were initially developed for the treatment of HIV infection, but they could be applied to other retroviruses.
The first integrase inhibitor approved by the U.S. Food and Drug Administration (FDA) was raltegravir (brand name Isentress), approved on October 12, 2007. Research results published in the New England Journal of Medicine on July 24, 2008, concluded that "raltegravir plus optimized background therapy provided better viral suppression than optimized background therapy alone for at least 48 weeks."
Since integrase inhibitors target a distinct step in the retroviral life cycle, they may be taken in combination with other types of HIV drugs to minimize adaptation by the virus. They are also useful in salvage therapy for patients whose virus has mutated and acquired resistance to other drugs.
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
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.
Drugs with this mechanism of action:Lemon/Vitamin a/Ascorbic acid/.alpha.-tocopherol acetate, dl-/Thiamine/Riboflavin/Niacin/Pyridoxine/Folic acid/Cyanocobalamin/Biotin/Pantothenic acid/Chromic cation/Iron/Magnesium cation/Zinc/Copper/Manganese/Selenium