Interaction between Warfarin and Levofloxacin: Case Series

Abstract

Warfarin is the most widely used oral anticoagulant and is indicated for many clinical conditions. Levofloxacin, a fluoroquinolone, is one of the most commonly prescribed antibiotics in clinical practice and is effective against Gram-positive, Gram-negative, and atypical bacteria. While small prospective studies have not revealed any significant drug-drug interaction between warfarin and levofloxacin, several case reports have indicated that levofloxacin may significantly potentiate the anticoagulation effect of warfarin. We report 3 cases of serious bleeding complications that appear to be the result of the interaction between warfarin and levofloxacin. Physicians should be aware of this potential interaction and use caution when prescribing levofloxacin to patients taking warfarin.

Drug interactions with phenprocoumon and the risk of serious haemorrhage: a nested case–control study in a large population-based German database

“…For warfarin, there have been discrepant findings regarding an interaction with quinolones [47]. Numerous case reports and case series [48][49][50][51][52] as well as population-based studies [35,46] have indicated that quinolones may potentiate the anticoagulant effect of warfarin and increased the risk of bleeding. In contrast, a large Canadian nested case-control study conducted in a cohort of chronic warfarin users did not find an elevated risk of hospitalisation for haemorrhage within 14 days after initiation of levofloxacin [53].…”

Retrospective assessment of potential interaction between levofloxacin and warfarin

“…Lastly, the clinical relevance of a potential interaction between warfarin and levofloxacin was reflected in a recent study by Vadlamudi et al [16], reporting three cases of severe bleeding complications (two hemopericardium and one retroperitoneal hematoma) occurring with concomitant administration of levofloxacin and warfarin, with one patient death resulting.…”

Drug and dietary interactions of warfarin and novel oral anticoagulants: an update

“…Fluoroquinolones have also been documented to interact with warfarin by inhibiting CYP1A2 [39][40][41][42][43][44][45][46]. Logistic regression of a case-crossover study done using US Medicaid data was performed to further investigate several documented warfarin interactions by measuring the increased risk of hospitalizations for gastrointestinal (GI) bleeding.…”