skip to main content

Allopurinol and azathioprine — GPhC CRA MCQ

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

HardDrug InteractionsAllopurinol and azathioprineGPhC CRA

A patient taking azathioprine for inflammatory bowel disease is prescribed allopurinol for gout prevention. The GP asks about interaction risk. 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: B — Allopurinol can greatly increase azathioprine toxicity

Allopurinol inhibits xanthine oxidase and reduces azathioprine metabolism. This can cause severe myelosuppression unless specialist dose reduction and monitoring are arranged. The other options either delay appropriate care, use an unsuitable medicine, or miss the main safety issue.

Reference: BNF