The Southern Medical Journal (SMJ) is the official, peer-reviewed journal of the Southern Medical Association. It has a multidisciplinary and inter-professional focus that covers a broad range of topics relevant to physicians and other healthcare specialists.

SMJ // Article

Case Report

Interaction between Warfarin and Levofloxacin: Case Series

Authors: Raja S. Vadlamudi, MD, MPH, Roger D. Smalligan, MD, MPH, Hassan M. Ismail, MD, MPH

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.


Key Points


* Although prospective studies have revealed no significant drug-drug interaction between warfarin and levofloxacin, multiple case reports have noted prolongation of anticoagulant effect with no mention of bleeding complications when the two medications are combined.


* Bleeding complications resulting from drug-drug interactions between warfarin and levofloxacin can be serious and life threatening.


* Physicians should be wary of this interaction and be cautious in prescribing levofloxacin to patients taking warfarin.

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