Antibacterial prescribing and warfarin: a review

Warfarin is the most commonly prescribed oral anticoagulant and is used in the management of thromboembolic disease. The practitioner is regularly faced with the need to prescribe concurrent antimicrobial therapy, either as prophylactic cover or in the therapeutic management of existing infection. Much has been written about the possible influence of antibiotics on the prothrombin time of patients taking warfarin, particularly in the form of isolated case reports, however evidence, in the form of controlled studies, is not always forthcoming. This review attempts to summarise current knowledge and, with reference to basic science, suggest possible management strategies when faced with a prescribing dilemma.