Management overview for MAOI poisoning

Drugs with monoamine oxidase inhibitory effects are primarily used as antidepressants. The irreversible nonselective monoamine oxidase inhibitors (MAOIs), phenelzine and tranylcypromine, are the focus of this monograph. These drugs have a narrow therapeutic index, and doses marginally above the therapeutic dose can be toxic or lethal. Although the reversible selective MAOIs (eg moclobemide) can be toxic, the effects are usually less severe and resolve faster. Some drugs have weak MAOI action (eg isoniazid, lamotrigine), but can still cause toxic effects. See isoniazid poisoning and lamotrigine poisoning for management of poisonings due to these drugs.

Toxicity can be due to a MAOI’s direct effects, interaction with serotonergic or adrenergic drugs, or interaction with food that contains tyramine (eg cheese, wine, preserved meat, yeast products). MAOI toxicity is usually delayed and gradual, but seizures, coma and cardiovascular collapse can occur abruptly.

If MAOI poisoning is suspected, urgently contact a clinical toxicologist or poisons information centre (13 11 26). Management involves supportive care, early gastrointestinal decontamination with activated charcoal, and treatment of complications. Avoid the use of serotonergic or adrenergic drugs.