Phenelzine is an irreversible non-selective inhibitor of monoamine oxidase. Although the exact mechanism of action has not been determined, it appears that the irreversible, nonselective inhibition of MAO by phenelzine relieves depressive symptoms by causing an increase in the levels of serotonin, norepinephrine, and dopamine in the neuron. Phenelzine is used for the treatment of major depressive disorder. Has also been used with some success in the management of bulimia nervosa.

Clorgiline is a monoamine oxidase (MAO) inhibitor. Specifically, it is an irreversible and selective inhibitor of MAO-A. Clorgiline was under investigation for antidepressant and anxiolytic potential but has never been marketed, likely due to efficacy concerns. It continues to see routine use as a molecular probe in biomedical research examining a number of neurological disease and cancer models. In addition to inhibiting the MAO-A receptor, it has also been found to bind to the sigma1 receptor, and with high affinity to the I2 imidazoline receptor.

LADOSTIGIL, a rasagiline derivative, is a reversible acetylcholinesterase and butyrylcholinesterase inhibitor with neuroprotective properties. It also acts as an irreversible brain monoamine oxidases inhibitor. It is under development for the treatment of neurodegenerative disorders like dementia and Alzheimer's disease.

Mofegiline (MDL 72,974A or (E)-2-(4-fluorophenethyl)-3-fluoroallylamine, hydrochloride), is a selective and irreversible inhibitor of monoamine oxidase type B (MAO-B) both in vitro and in vivo. In addition, mofegiline inhibits semicarbazide-sensitive amine oxidase activity from human serum and saphenous vein. In phase II studies, MDL 72,974A is proving to be a useful adjunct to conventional therapy of Parkinson's disease. It seems mofegiline development was discontinued.

Pargyline is an irreversible selective monoamine oxidase (MAO)-B inhibitor, which possesses higher selectivity to this isoform in comparison with MAO-A. It was approved under brand name eutonyl for the treatment hypertension, but then this drug was discontinued.

ETRYPTAMINE (MONASE®), similar to the hallucinogenic tryptamines, is an inhibitor of monoamine oxidase, introduced for use as an antidepressant. It was withdrawn from the market due to problems with agranulocytosis and other side effects. However, it's activity is still under scientific investigation.

PHENIPRAZINE is a monoamine oxidase inhibitor of the hydrazine chemical class that was used for the treatment of depression, schizophrenia, and also as a long-acting coronary vasodilator in patients suffering from angina pectoris. PHENIPRAZINE was discontinued due to toxicity concerns such as jaundice, amblyopia, and optic neuritis.

Safrazine (Safra) is a non-selective, irreversible monoamine oxidase inhibitor (MAOI) of the hydrazine class that was introduced as an antidepressant in the 1960s. Safrazine and electroconvulsive therapy were shown to be effective in the treatment of antidepressant-resistant depressions (ARD) but had the drawbacks of the high incidence of moderate or severe adverse reactions and high relapse rates, respectively. The use of safrazine was discontinued.

Lazabemide is a reversible and selective inhibitor of monoamine oxidase B (MAO-B) that was under clinical development against Parkinson's disease, Alzheimer's disease and as an aid to smoking cessation. The development of the drug was discontinued due to liver toxicity.