Phenelzine

Phenelzine
Phenethylhydrazine
Empiric formula	C8H12N2
Molecular weight	139.19
Bioavailability	?
Metabolism	Liver
Elimination half life	1.2 hours
Excretion	Urine
Pregnancy category	C (USA) B3 (Aus)
Delivery	Oral
Indicated for: anxiety disorder atypical depression bulimia refractory depression social phobia

Phenelzine is an antidepressant drug that belongs to the monoamine oxidase inhibitor class of drugs.

Table of contents

1 Mode of action 2 Pharmacokinetics 3 Side effects

Mode of action

Phenelzine is a derivative of hydrazine, which is phenylethylenamine-like moiety and similar to normal substrates of MAO. When MAO tries to oxidize phenelzine, this hydrazine-moiety binds covalently to the enzyme, thus inactivating it irreversibly. Phenelzine is a non-selective MAO-inhibitor, it inhibits both MAO-A and MAO-B.

Pharmacokinetics

Phenelzine is administered orally as phenelzine sulphate and it is rapidly absorbed form the gastro-intestinal tract. Although phenelzine has a fairly short half-life, its effect lasts for several, until new functional MAO-enzymes have been produced by the body. Phenelzine is acetylated in the liver and its metabolites are excreted in the urine.

Side effects

Common side effects include orthostatic hypotension, dizziness, headache, fatigue and gastro-intestinal disturbances. Phenelzine can cause, though rarely, severe hepatotoxicity, most likely due to its hydrazine group.

As with other MAOIs, tyramine-containing foods can cause a cheese reaction, which is a severe hypertensive crisis, so users of phenelzine must adhere to rigid dietary guidelines. This hypertensive crisis is characterised by severe headache and rapid rise in blood pressure, which can cause cardiac failure and intracranial hemorrhage.