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Drug Interaction (Statin + Macrolide) — PSA MCQ

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HardPharmacologyDrug Interaction (Statin + Macrolide)PSAMRCGP AKTUKMLAPARAMRCP Part 1

A patient with eGFR 24 mL/min/1.73 m² takes colchicine for gout prophylaxis. Clarithromycin is proposed for an infection. What is the most appropriate prescribing response?

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Correct answer: C — Avoid the combination because severe colchicine toxicity can occur

C is correct. Clarithromycin inhibits CYP3A4 and P-glycoprotein, pathways involved in colchicine disposition, and can markedly increase colchicine exposure. Renal impairment further reduces the margin of safety, creating a risk of fatal toxicity with gastrointestinal symptoms, marrow suppression, neuromyopathy and multiorgan failure. Dose separation does not prevent the metabolic and transporter interaction. The combination should be avoided and an appropriate non-interacting antimicrobial selected when possible, with the indication and cultures reviewed. New diarrhoea, vomiting, weakness or cytopenia in an exposed patient requires urgent assessment rather than an automatic colchicine dose increase.

Reference: BNF, colchicine interactions and cautions: https://bnf.nice.org.uk/drugs/colchicine/