Comparative pharmacokinetics of coumarin anticoagulants XXIV: Effect of treatment with phenobarbital on serum protein binding of warfarin and dicumarol in rats.

Rats were treated with the enzyme inducer phenobarbital to determine if it would affect the serum protein binding of warfarin and dicumarol, possibly by changing the rate of formation or elimination of endogenous inhibitor(s). Daily administration of phenobarbital, 75 mg/kg, for 4 days increased relative liver size (a concomitant of enzyme induction) but had no apparent effect on the serum protein binding of warfarin and dicumarol.