Phenelzine

Do not use during pregnancy, especially during the first and last trimesters, unless there are compelling reasons. There is no evidence as to drug safety in human pregnancy nor is there evidence from animal work that it is free from hazard.

It is not known if phenelzine is excreted in breast milk. Because of the potential for serious adverse effects to the infant, a decision should be made whether to discontinue the drug or not to breast-feed.

Produces adverse effects on driving ability.

Side-effects tend to be mild or moderate in severity, often subsiding as treatment continues, and can be minimised by adjusting dosage; rarely is it necessary to discontinue phenelzine.

The most important reaction associated with phenelzine is the occurrence of hypertensive crises, which have been associated with intracranial bleeding and have sometimes been fatal.

Cases of suicidal ideation and suicidal behaviours have been reported during phenelzine therapy or early after treatment discontinuation.

Common side-effects include: dizziness, drowsiness, weakness and fatigue, oedema, gastro-intestinal disturbances (nausea, vomiting, dryness of the mouth, constipation), insomnia, blurred vision, adverse effects on driving ability, postural hypotension, twitching, myoclonic movements, hyperreflexia, elevated serum transaminases and anorgasmia.

Uncommon side-effects are headache, nervousness, euphoria, paraesthesia, sweating, increased appetite and weight, rash, pruritus, difficulty in micturition, muscle tremor, peripheral neuritis, behavioural changes, arrhythmias, convulsions, impotence and delayed ejaculation, purpura, blood dyscrasias, jitteriness, palilalia, nystagmus, hypernatraemia, glaucoma, lupus-like illness, confusion, hallucinations and elevated liver enzymes.

Other severe side-effects have been reported very rarely, including isolated reports in some cases. These include: ataxia, shock-like coma, toxic delirium, neuroleptic malignant syndrome (occasionally fatal), manic reaction, acute anxiety reaction, precipitation of schizophrenia, transient respiratory and cardiovascular depression following ECT, fatal progressive necrotising hepatocellular damage, reversible jaundice, hypermetabolic syndrome, oedema of the glottis and fever associated with increased muscle tone.

Hyponatraemia (usually in the elderly and possibly due to inappropriate secretion of antidiuretic hormone) has been associated with all types of antidepressants and should be considered in all patients who develop drowsiness, confusion or convulsions while taking an antidepressant.

Withdrawal may be associated with nausea, vomiting and malaise. An uncommon withdrawal syndrome following abrupt withdrawal of phenelzine has been infrequently reported. Signs and symptoms of this syndrome generally commence 24 to 72 hours after drug discontinuation and may vary from vivid nightmares and agitation to frank psychosis and convulsions. This syndrome generally responds to reinstitution of low-dose phenelzine therapy followed by cautious downward titration and discontinuation.