Monoamine oxidase inhibitors

Main indications

• Depressive illness (rarely used)

Mechanism of action

• Irreversible (phenelzine) or reversible (moclobemide) inhibitors of MAO-A and B

Contraindications and cautions

• Contraindicated in pregnancy (increased risk of neonatal malformations) and manic phase of bipolar disorder
• Use with great caution in the elderly

Adverse effects

• 'Cheese reaction' - hypertensive crisis caused by inhibition of MAO-A in gut (and liver) by irreversible inhibitors preventing breakdown of dietary tyramine
• Potentiates effects of other drugs (e.g. barbiturates) by decreasing their metabolism
• Insomnia
• Postural hypotension
• Peripheral oedema

Administration

• PO

Tricyclic antidepressants

• e.g. imipramine, dosulepin, amitriptyline, lofepramine

Main indications

• Depressive illness
  • Used 3rd/4th line nowadays due to toxicity in overdose plus side effects