Phenobarbitone and warfarin interaction results in: March 2005
Ans. B: Increased metabolism of warfarin Barbiturates increase the metabolism of oral anticoagulants, resulting in reduced anticoagulation effects. If co-administration is unavoidable, monitoring of INR and adjustment of anticoagulant dose is needed. An increase in anticoagulant dose (approximately 30-60%) may be needed when adding a barbiturate. Withdrawal of barbiturates will result in reduced anticoagulant requirement over several weeks; a reduction in the anticoagulant dose may be needed to prevent bleeding complications
Increased absorption of warfarin
Increased metabolism of warfarin
Displacement of warfarin from the binding site
All of the above