Reversible inhibitor of monoamine oxidase A

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 in the United States. 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.

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 combined with almost any antidepressant or stimulant, common migraine medications, certain herbs, or even most cold medicines (including decongestants, antihistamines, and cough syrup).

Loading... please wait...

This page contains text from Wikipedia, the Free Encyclopedia - https://wn.com/Reversible_inhibitor_of_monoamine_oxidase_A

Inhibitor

Inhibitor or inhibition may refer to:

In biology

Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity

In chemistry

Corrosion inhibitor, a substance that decreases the rate of metal oxidation

Reaction inhibitor, a substance that prevents or decreases the rate of a chemical reaction

In psychology and neurology

Cognitive inhibition, the mind's ability to tune out irrelevant stimuli

Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotransmitter

Inhibition of return, a feature of attention

Inhibition theory, a theory pertaining to the performance of a mental task

Latent inhibition, a term used in classical conditioning

Lateral inhibition, a neural mechanism that increases contrast between active and (neighbouring) inactive neurons

Memory inhibition, processes that suppress or interfere with specific memories

Sexual inhibition, reservations relating to sexual practices

Social inhibition, a conditioned fear reaction to social marginalization or isolation

Reaction inhibitor

A reaction inhibitor is a substance that decreases the rate of, or prevents, a chemical reaction. A catalyst, in contrast, is a substance that increases the rate of a chemical reaction.

Examples

Added acetanilide slows the decomposition of drug-store hydrogen peroxide solution, inhibiting the reaction

2H
2O
2 → 2H
2O + O
2, which is catalyzed by heat, light, and impurities.

Inhibition of a catalyst

An inhibitor can reduce the effectiveness of a catalyst in a catalysed reaction (either a non-biological catalyst or an enzyme). E.g., if a compound is so similar to (one of) the reactants that it can bind to the active site of a catalyst but does not undergo a catalytic reaction then that catalyst molecule cannot perform its job because the active site is occupied. When the inhibitor is released, the catalyst is again available for reaction.

Inhibition and catalyst poisoning

Inhibition should be distinguished from catalyst poisoning. An inhibitor only hinders the working of a catalyst without changing it, whilst in catalyst poisoning the catalyst undergoes a chemical reaction that is irreversible in the environment in question (the active catalyst may only be regained by a separate process).