Answer the following questions using the information given i

Answer the following questions using the information given in the scenario. Phenobarbital is a potent inducer of cytochrome P450-2C9. Warfarin, an anticoagulant with a narrow therapeutic window, is a substrate for the same isozyme of cytochrome P450. Toxic blood levels of warfarin can cause dangerous uncontrolled bleeding

Question: Question: A patient determined by genetic testing to produce a less active isoform of P450-2C9 would require what in a therapeutic setting, all else being equal?

a)A shorter duration of warfarin treatment than is generally safe.

b) Coadministration of a P450 inhibitor.

c) No change from standard therapy.

d) A greater than standard dose of warfarin.

e) A smaller than standard dose of warfarin.

Please include an explanation! (Note: I already tried choices b and d and they were incorrect)

Solution

A shorter duration of warfarin treatment that is generally safe.

Patient produce a less active isoform of P450-2C. Here it indicates that lesser amount of enzyme is formed and warfarin having narrow therapeutic window, cannot be used for longer time as therapeutic treatment.

Therefore better option would be to use warfarin for shorter period.