OBJECT DRUGS

Anticoagulants, Oral:

• Acenocoumarol
• Warfarin (Coumadin, etc.)

PRECIPITANT DRUGS

Enzyme Inhibitors:

• Alcohol (intoxication)
• Azapropazone
• Sulfinpyrazone (Anturane)

Comment:

Acute alcohol intoxication can markedly increase the effect of warfarin. Azapropazone and sulfinpyrazone markedly increase the anticoagulant response to warfarin, due primarily to inhibition of CYP2C9 (assume that acenocoumarol interacts similarly until proved otherwise).

Class 1: Avoid Combination

• Avoid: Patients receiving oral anticoagulants should avoid alcohol intoxication, but available evidence suggests that modest alcohol intake (e.g., 1-2 drinks/day) has little or no effect on warfarin response. Since azapropazone and sulfinpyrazone can markedly increase warfarin response, concurrent use should be avoided.