Moderate
Probable
Descripción
Azithromycin can potentiate the anticoagulant effect of warfarin, leading to elevated INR and increased bleeding risk during and shortly after the antibiotic course.
Mecanismo
Proposed mechanisms include inhibition of CYP1A2 and possible disruption of gut flora that synthesize vitamin K2 (menaquinones), reducing vitamin K availability for clotting factor synthesis.
Relevancia clínica
Case reports and pharmacovigilance data document supratherapeutic INR elevations; major bleeding has been reported.
Manejo clínico
Monitor INR within 3–5 days of starting and after completing azithromycin; adjust warfarin dose if INR rises above target range.