skip to main content

Drug Interaction CBZ-Erythromycin — RACP Paediatrics MCQ

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

ModerateNeurology & DevelopmentDrug Interaction CBZ-ErythromycinRACP Paediatrics

A 10-year-old with epilepsy well controlled on carbamazepine is prescribed erythromycin for an URTI. He becomes drowsy and ataxic. What has occurred?

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

Reveal the answer and explanation

Correct answer: E — Drug interaction: erythromycin inhibits CYP3A4 causing elevated carbamazepine levels and toxicity

Erythromycin (and other macrolides) inhibits CYP3A4, reducing carbamazepine metabolism and causing toxicity. Azithromycin has less CYP interaction.

Reference: AMH Children's Dosing Companion – 2024