Description
Clindamycin may enhance the anticoagulant effect of warfarin by disrupting vitamin K-producing gut flora, leading to unpredictable INR elevations and increased bleeding risk during and shortly after the antibiotic course.
Mécanisme
Clindamycin has broad activity against anaerobic gut bacteria that synthesise menaquinones (vitamin K2); reduction in gut flora vitamin K production augments warfarin's anticoagulant effect without altering warfarin pharmacokinetics directly.
Signification clinique
Case reports and observational data associate clindamycin use with supratherapeutic INR values in anticoagulated patients; the magnitude is variable and difficult to predict.
Prise en charge
Monitor INR within 3–5 days of starting clindamycin; reduce warfarin dose if INR rises above the therapeutic range; maintain consistent dietary vitamin K intake during antibiotic therapy.