A patient of DVT was stabilized on warfarin. This person was given phenobarbitone. Which of the following is the likely interaction between the two drugs?: (A) Phenobarbitone increases the absorption of warfarin, (B) Phenobarbitone increases the metabolism of warfarin, (C) Phenobarbitone displaces warfarin from plasma protein binding sites, (D) All of the above
Answer is B. -- Barbiturates like phenobarbitone are powerful enzyme inducers -- These increase the metabolism of warfarin and decrease its anticoagulant effect.