Phenelzine

The MAOIs comprise a chemically heterogeneous group of drugs that have in common the ability to block oxidative deamination of naturally occurring monoamines.

MAOIs exert their effects mainly in organ systems influenced by sympathomimetic amines and 5-HT.

The MAOIs in clinical use are site-directed irreversible inhibitors. The hydrazines attack and inactivate the flavin prosthetic group following their oxidation to reactive intermediates by MAO.

The capacity of MAOIs to act as antidepressants has most often been assumed to reflect the increased availability of one or more monoamines in the CNS or sympathetic nervous system.

All the currently employed MAOIs are readily absorbed when given by mouth. These drugs produce maximal inhibition of MAO in biopsy samples from man within 5 to 10 days. There is little information on their pharmacokinetics. However, their biological activity is prolonged due to the characteristics of their interactions with the enzyme.

The hydrazide MAOIs are thought to be cleaved with resultant liberation of active products. They are inactivated primarily by acetylation.

There are no pre-clinical safety data of relevance to the prescriber which are additional to those already included in other sections.