Question

A patient is prescribed phenobarbital for epilepsy. Phenobarbital is a potent inducer of the cytochrome P450 enzyme system. If this patient is also taking warfarin, what effect would the addition of phenobarbital likely have on their warfarin requirement and INR?

Accepted Answer

Increase warfarin requirement, Decrease INR

Answer

Decrease warfarin requirement, Increase INR

Answer

No effect on warfarin requirement or INR

Answer

Increase warfarin requirement, Increase INR

Answer

Decrease warfarin requirement, Decrease INR

Practice question

A patient is prescribed phenobarbital for epilepsy. Phenobarbital is a potent inducer of the cytochrome P450 enzyme system. If this patient is also taking warfarin, what effect would the addition of phenobarbital likely have on their warfarin requirement and INR?