Monoamine Oxidase Inhibitors (maois): From 1 Different Sources
These are drugs that destroy, or prevent the action of, monoamine oxidase (MAO). Monoamines, which include NORADRENALINE and tyramine, play an important part in the metabolism of the BRAIN, and there is some evidence that excitement is due to an accumulation of monoamines in the brain. MAO is a naturally occurring ENZYME which is concerned in the breakdown of monoamines. MAOIs were among the earliest ANTIDEPRESSANT DRUGS used, but they are now used much less than tricyclic and related antidepressants, or SELECTIVE SEROTONIN-REUPTAKE INHIBITORS (SSRIS) and related antidepressants, because of the dangers of dietary or drug interactions – and because MAOIs are less e?ective than these two groups.
An excessive accumulation of monoamines can induce a dangerous reaction characterised by high blood pressure, palpitations, sweating and a feeling of su?ocation. Hence the care with which MAOI drugs are administered. What is equally important, however, is that in no circumstances should a patient receiving any MAOI drug eat cheese, yeast preparations such as Marmite, tinned ?sh, or high game. The reason for this ban is that all these foodstu?s contain large amounts of tyramine which increases the amount of certain monoamines such as noradrenaline in the body. (See MENTAL ILLNESS.)
There are also certain drugs, such as AMPHETAMINES and PETHIDINE HYDROCHLORIDE, which must not be taken by a patient who is receiving an MAOI drug. The MAOIs of choice are phenelzine or isocarboxazid because their stimulant effects are less than those of other MAOIs, making them safer.
These are drugs that inhibit the production of acid in the stomach by blocking a key enzyme system, known as the PROTON PUMP, of the parietal cells of the stomach. The drugs include omeprazole, lansoprazole and pantoprazole, and they are the treatment of choice for oesophagitis (erosion and stricture – see under OESOPHAGUS, DISEASES OF); for the short-term treatment for gastric ulcer (see under STOMACH, DISEASES OF) and DUODENAL ULCER; and, in combination with ANTIBIOTICS, for the eradication of Helicobacter pylori.... proton-pump inhibitors
See ANGIOTENSIN-CONVERTING ENZYME (ACE) INHIBITORS.... ace inhibitors
The ENZYME that converts angiotensin I to angiotensin II (see ANGIOTENSIN) is called angiotensin-converting enzyme. Angiotensin II controls the blood pressure and is the most potent endogenous pressor substance produced in the body; angiotensin I has no such pressor activity. Inhibition of the enzyme that converts angiotensin I to angiotensin II will thus have marked effects on lowering the blood pressure, and ACE inhibitors have a valuable role in treating heart failure when thiazides and beta blockers cannot be used or fail to work, especially after myocardial infarction (see HEART, DISEASES OF). Captopril was the ?rst ACE inhibitor to be synthesised: it reduces peripheral resistance by causing arteriolar dilatation and thus lowers blood pressure. Other drugs such as enalapril, lisinopril, cilazapril, quinapril and ramipril have since been developed. Some kidney disorders increase the production of angiotensin II and so cause HYPERTENSION.... angiotensin-convertingenzyme (ace) inhibitors
A group of drugs that stop the action of the ENZYME, aromatase. This enzyme converts androgens (see ANDROGEN) to OESTROGENS. If this conversion is inhibited, the concentrations of oestrogens in the body are reduced – so these drugs operate against tumours, such as breast cancer, that depend on oestrogen for their growth. Aromatase inhibitors include anastrazole and formestane, and they are usually prescribed as second-line treatment after TAMOXIFEN, the prime drug treatment for breast cancer.... aromatase inhibitors
This stands for cyclo-oxygenase 2 inhibitors – a class of drugs used in treating ARTHRITIS – of which the most well-used is celecoxib. Their main claim is that they are less likely to cause gastrointestinal disturbance than NONSTEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS). In 2001, the National Institute for Clinical Excellence (NICE) recommended that they should not be used routinely in rheumatoid arthritis or osteoarthritis but only in patients with a history of peptic ulcer or gastrointestinal bleeding. They should also be considered in persons over the age of 65 taking other drugs which could cause gastrointestinal bleeding, those who are very debilitated, and those who are taking maximum doses of NSAIDs. In 2005, rofecoxib was withdrawn because of concerns about cardiac side-effects.... cox-2 inhibitors
See COX-2 INHIBITORS.... cyclo-oxygenase-2 selective inhibitors
See MONOAMINE OXIDASE INHIBITORS (MAOIS).... maois
A new group of drugs which, in combination with antiviral agents, are used to treat AIDS (see AIDS/HIV). They inhibit the activity of PROTEASE, an enzyme produced by HIV, and which breaks down proteins. The drugs have recently been introduced: those in use are indinavir, nel?navir, ritonavir and saquinavir.... protease inhibitors
These ANTIDEPRESSANT DRUGS have few antimuscarinic effects (see ANTIMUSCARINE), but do have adverse effects of their own – predominantly gastrointestinal. They are, however, much safer in overdose than the tricyclic antidepressants, which is a major advantage in patients who are potentially suicidal. Examples are citalopram, used to treat panic disorders, as well as depressive illness; FLUOXETINE; and PAROXETINE. (See also MENTAL ILLNESS.)... selective serotonin-reuptake inhibitors (ssris)
A class of drugs used in the treatment of diseases, including HIV infection, that are caused by retroviruses. The drugs affect the ability of the virus to reproduce by blocking reverse transcriptase, a key enzyme. Drugs include lamivudine, zidovudine (AZT), efavirenz, and stavudine.... reverse transcriptase inhibitors
drugs that act by inhibiting the calcium-dependent protein *phosphatase calcineurin, an enzyme that initiates a sequence of events that bring about activation of T *lymphocytes. The group includes *ciclosporin and *tacrolimus, which are major maintenance immunosuppressants used in transplantation. Topical calcineurin inhibitors (e.g. tacrolimus, pimecrolimus [Elidel]) are used in the treatment of eczema when topical steroids have failed or are contraindicated. Stinging is a common transient side-effect, and reactivation of infections may occur.... calcineurin inhibitors
a group of *oral hypoglycaemic drugs used in the treatment of type 2 diabetes mellitus. Through inhibiting the enzyme dipeptidyl peptidase-IV they enhance the action of *glucagon-like peptide-1. Five drugs in this group are currently licensed for use in the UK: sitagliptin, vildagliptin, saxagliptin, linagliptin, and alogliptin.... dpp-iv inhibitors
(MAO) an enzyme that catalyses the oxidation of a large variety of monoamines, including adrenaline, noradrenaline, and serotonin. Monoamine oxidase is found in most tissues, particularly the gastrointestinal tract and nervous system, and exists in two forms in humans: monoamine oxidase A primarily breaks down noradrenaline and serotonin, whereas monoamine oxidase B primarily degrades dopamine. Drugs that act as inhibitors of monoamine oxidase A may be used in the treatment of depression (see MAO inhibitor); monoamine oxidase B inhibitors are used to treat Parkinson’s disease.... monoamine oxidase
n. see oxidoreductase.... oxidase
see calcineurin inhibitors.... topical calcineurin inhibitors
Health Encyclopedia