A patient receiving anti-coagulant therapy with warfarin was prescrbed the anti-epileptic drug phenobarbital by his physician.

Question

A patient receiving anti-coagulant therapy with warfarin was prescrbed the anti-epileptic drug

phenobarbital by his physician. Which of the following options should be considerad to optimize

drug dosage for?

Answer 1

Phenobarbital is an inducer of hepatic cytochrome p450, which metabolizes warfarin. So a previously therapeutic warfarin dose may be less effective after phenobarbitals is started. Increased frequency of INR monitoring is indicated to allow adjustment of warfarin dose if needed.