Feprazone Warfarin

The anticoagulant effects of warfarin are markedly increased by azapropazone, oxyphenbutazone and phenylbutazone. Concurrent use should be avoided because serious bleeding can occur. Feprazone appears to interact similarly. 

Five patients stabilised on warfarin had a mean prothrombin time rise from 29 to 38 seconds after taking feprazone 200 mg twice daily for 5 days, despite a 40% reduction in the warfarin dosage (from 5 to 3 mg daily). Four days after feprazone was stopped, their prothrombin times were almost back to usual. The interaction with feprazone was less marked than that with phenylbutazone. ... 

Chierichetti S, Bianchi G, Cerri B. Comparison of feprazone and phenylbutazone interaction with warfarin inman. CurrTherRes ( 915) 18, 568-72. 

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