Rifampicin-DOAC Interaction — EECC MCQ

Correct answer: A — Rifampicin is a potent inducer of CYP3A4 and P-glycoprotein, significantly reducing apixaban plasma levels and potentially rendering anticoagulation ineffective — concomitant use should be avoided

Rifampicin is one of the strongest inducers of CYP3A4 and P-glycoprotein, dramatically increasing the metabolism and efflux of DOACs. For apixaban and rivaroxaban (CYP3A4 and P-gp substrates), concomitant rifampicin reduces plasma levels by 50-55%, potentially rendering anticoagulation ineffective and exposing the patient to stroke risk. The ESC 2024 AF Guidelines list strong CYP3A4/P-gp inducers (rifampicin, carbamazepine, phenytoin, St John's wort) as contraindications to DOAC co-administration. For patients requiring TB treatment and anticoagulation, warfarin (with INR monitoring and dose adjustment) or an alternative anti-TB regimen (avoiding rifampicin) should be discussed with the TB team.

Reference: ESC (2024): AF Guidelines; BNF DOAC Interactions