skip to main content

MAOI and SSRI switching — GPhC CRA MCQ

Instant feedback + full explanation. One question, done properly.

HardDrug InteractionsMAOI and SSRI switchingGPhC CRA

A GP sends a prescription for fluoxetine 20mg daily for a patient who stopped phenelzine yesterday because of postural hypotension. The patient has severe depression but is clinically stable today. The GP asks whether the prescription can be dispensed. What is the most important interaction to flag?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: A — contact the GP because a washout period is required after phenelzine before starting fluoxetine

Phenelzine is an irreversible MAOI and requires an adequate washout period before starting serotonergic antidepressants such as fluoxetine. Starting too soon can precipitate serious serotonin toxicity or hypertensive reactions. The pharmacist should contact the prescriber to clarify the intended switching plan. Concurrent use or rapid switching is unsafe.

Reference: BNF