Selegiline-SSRI Serotonin Syndrome — SCE Neurology MCQ

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HardMovement DisordersSelegiline-SSRI Serotonin SyndromeSCE Neurology

A 60-year-old man with PD presents with acute confusion, fever, and autonomic instability (tachycardia, labile BP, diaphoresis). He was recently started on selegiline by his GP. His other medications include co-careldopa and citalopram. What dangerous drug interaction may be occurring?

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Correct answer: D — Serotonin syndrome from the combination of selegiline (MAO-B inhibitor) and citalopram (SSRI)

Selegiline is a MAO-B inhibitor that at higher doses can lose selectivity and inhibit MAO-A. The combination of MAO inhibitors with SSRIs (citalopram) can precipitate serotonin syndrome — a life-threatening condition characterised by altered mental status, autonomic instability, neuromuscular excitability (clonus, hyperreflexia, myoclonus), and hyperthermia. BNF and MHRA explicitly warn against this combination. Management includes stopping both drugs, supportive care, and cyproheptadine for severe cases. B: NMS is caused by dopamine antagonists. C: Drug-induced parkinsonism has gradual onset. D: No lithium is prescribed. E: Anticholinergic crisis has dry skin, urinary retention, mydriasis.

Reference: BNF Drug Interactions – MAO-B Inhibitors and SSRIs; MHRA Safety Alert