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Published on: July 24, 2021
Interactions between warfarin and three commonly prescribed fluoroquinolones
Douglas N Carroll1, Dana G Carroll
1Department of Pharmacy Practice, Harrison School of Pharmacy, Auburn University, Tuscaloosa, AL 35487, USA. carrodn@auburn.edu
The Annals of Pharmacotherapy
|April 17, 2008
Summary
Concomitant warfarin and fluoroquinolone therapy does not consistently increase anticoagulant effects. However, some patients experience significant increases, necessitating frequent monitoring of warfarin therapy to prevent complications.
Area of Science:
- Pharmacology
- Drug Interactions
- Clinical Pharmacy
Background:
- Warfarin is a widely used anticoagulant.
- Fluoroquinolones are broad-spectrum antibiotics.
- Potential drug interactions between warfarin and fluoroquinolones require investigation.
Purpose of the Study:
- To critically evaluate the potential for increased anticoagulant response during combined warfarin and fluoroquinolone therapy.
- To synthesize existing literature on warfarin-fluoroquinolone interactions.
Main Methods:
- Comprehensive literature search of PubMed, International Pharmaceutical Abstracts, and MEDLINE.
- Inclusion of all publication types reporting on warfarin and fluoroquinolone (ciprofloxacin, levofloxacin, moxifloxacin) use in human participants.
- Analysis of studies reporting prothrombin time (PT) or international normalized ratio (INR) values.
Main Results:
- Twenty-two publications were reviewed, including case reports, cohort studies, and prospective investigations.
- Reported changes in PT/INR were variable and inconsistent.
- While mean increases in PT/INR were clinically insignificant in structured reports, some patients showed significant elevations, particularly within the first week of fluoroquinolone use.
Conclusions:
- Current data do not support a consistent increase in anticoagulant effect with concurrent warfarin and common fluoroquinolone use.
- Despite inconsistent findings, prudent clinical practice suggests more frequent monitoring of anticoagulation during this drug combination.
- Rare but serious outcomes, including death from bleeding complications, highlight the importance of vigilance.
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