J Korean Med Sci.  2010 Mar;25(3):337-341. 10.3346/jkms.2010.25.3.337.

Risk Factors of Drug Interaction between Warfarin and Nonsteroidal Anti-Inflammatory Drugs in Practical Setting

• Choi KH
• Kim AJ
• Son IJ
• Kim KH
• Kim KB
• Ahn H
• Lee EB

• KMID: 1778025
• DOI: http://doi.org/10.3346/jkms.2010.25.3.337

Abstract

Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to interact with the oral anticoagulant warfarin and can cause a serious bleeding complication. In this study, we evaluated the risk factors for international normalized ratio (INR) increase, which is a surrogate marker of bleeding, after addition of an NSAID in a total of 98 patients who used warfarin. Patient age, sex, body mass index, maintenance warfarin dose, baseline INR, coadministered medications, underlying diseases, and liver and kidney functions were evaluated for possible risk factors with INR increase > or =15.0% as the primary end-point. Of the 98 patients, 39 (39.8%) showed an INR elevation of > or =15.0% after adding a NSAID to warfarin therapy. Multivariate analysis showed that high maintenance dose (>40 mg/week) of warfarin (P=0.001), the presence of coadministered medications (P=0.024), the use of meloxicam (P=0.025) and low baseline INR value (P=0.03) were the risk factors for INR increase in respect to NSAID-warfarin interaction. In conclusion, special caution is required when an NSAID is administered to warfarin users if patients are taking warfarin >40 mg/week and other medications interacting with warfarin.

Keyword

Warfarin; Anti-Inflammatory Agents, Non-Steroidal; Drug Interactions

MeSH Terms

Adult
Aged
*Anti-Inflammatory Agents, Non-Steroidal/adverse effects/therapeutic use
*Anticoagulants/adverse effects/therapeutic use
Drug Interactions
Female
Hemorrhage/*chemically induced
Humans
International Normalized Ratio
Male
Middle Aged
Retrospective Studies
Risk Factors
Thiazines/adverse effects/therapeutic use
Thiazoles/adverse effects/therapeutic use
*Warfarin/adverse effects/therapeutic use
Anti-Inflammatory Agents, Non-Steroidal
Anticoagulants
Thiazines
Thiazoles
Warfarin

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