Piroxicam Acenocoumarol

Acenocoumarol Piroxicam R t S Reduced metabolic clearance of R enantiomer t 79... 

In patients stabilised on acenocoumarol, piroxicam 20 mg daily for 2 weeks increased the effects of acenocoumarol in 4 out of 11 patients the effect was considered mild in 3 patients, and significant in the fourth, although no specific values were gi ven. An increased prothrombin ratio has been seen in another patient. A further patient taking acenocoumarol developed gastrointestinal bleeding 3 days after starting to take piroxicam 20 mg daily. His INR rose from 2.2 to 6.5. ... 

Acenocoumarol. In a single-dose study in healthy subjects, when piroxicam 40 mg was given with acenocoumarol 4 mg the AUC of the more active A-isomer was increased by 47% and its maximum plasma level was increased by 28%. ... 

Piroxicam inhibits the metabolism of the active J -acenocoumarol, but its effect on the metabolism of warfarin is unknown. Lomoxicam inhibited the metabolism of warfarin, but not acenocoumarol, in vitro In addition NSAIDs have antiplatelet effects, which can prolong bleeding if it occurs. They may also cause gastrointestinal toxicity. Because of these effects, in patients taking anticoagulants, the risk of bleeding is increased by NSAIDs , (p.427). 

Bonnabry P, Desmeules J, Rudaz S, Leemann T, Veudiey J-L, Dayer P. Stereoselective interaction between piroxicam and acenocoumarol. BrJ Clin Pharmacol (1996) 41, 525-30. 

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