Reversible inhibitor of monoamine oxidase A

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Skeletal formula of moclobemide, the prototypical reversible inhibitor of monoamine oxidase type A

Ribbon diagram of a monomer of human MAO-A, with FAD and clorgiline bound, oriented as if attached to the outer membrane of a mitochondrion. From PDB 2BXS.

Reversible inhibitors of monoamine oxidase type-A (RIMAs) are a family of psychiatric drugs and natural compounds that inhibit monoamine oxidase temporarily and reversibly. They are mostly used for alleviating depression and dysthymia. Because their action is short-lived and selective, they have a better safety profile than the older MAOIs.

Moclobemide, brofaromine, and some beta-carbolines, such as harmaline, are examples of RIMAs.^[1][2]

[edit] Functionality and safety

RIMAs, a subset of monoamine oxidase inhibitors (MAOIs), inhibit only isoenzyme A and are reversible. They are displaced from monoamine oxidase in the presence of tyramine,^[1] rather than inhibiting its breakdown in the liver as general MAOIs do. Additionally, isoenzyme B remains free and continues to metabolize tyramine in the stomach, although this is less significant than the liver action. Thus, a special diet does not need to be so strictly adhered to, although eating excessively large amounts of tyramine-containing foods is 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 when combined with almost any antidepressant or stimulant, common migraine medications, certain herbs, or even most cold medicines (including decongestants, antihistamines, and cough syrup).^{[citation needed]}

[edit] References

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