Letter to the Editor

Further Evidence of a Clinically Significant Levofloxacin-Warfarin Interaction

Authors: Jeffrey J. Glasheen, MD, Allan V. Prochazka, MD, MSc

Abstract

To the Editor:


We read with interest the article by Vadlamudi et al1 regarding the three cases of significant bleeding in patients concomitantly using warfarin and levofloxacin. The authors note that scant data even support a drug-drug interaction, let alone significant bleeding outcomes. Based on their report they recommend prudence in monitoring simultaneous use of these two medications. However, we believe the authors overlooked some significant data that suggest that a clinically significant interaction does occur and should further bolster this recommendation for vigilance.

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References

1. Vadlamudi RS, Smalligan RD, Ismail HM. Interactions between warfarin and levofloxacin: case series. South Med J 2007;100:720–724.
 
2. Yamreudeewong W, Lower DL, Kilpatrick DM, et al. Effect of levofloxacin coadministration on the international normalized ratios during warfarin therapy. Pharmacotherapy. 2003;23:333–338.
 
3. Glasheen JJ, Fugit RV, Prochazka AV. Effect of levofloxacin coadministration on the international normalized ratios during warfarin therapy—a comment (letter). Pharmacotherapy 2003;23:1079–1080.
 
4. Glasheen JJ, Fugit RV, Prochazka AV. The risk of overanticoagulation with antibiotic use in outpatients on stable warfarin regimens. J Gen Intern Med 2005;20:653–656.