Effect of phenobarbital in a case of extrahepatic cholestasis.

Phenobarbital was administered to a patient with extrahepatic biliary obstruction who was initially thought to have cholestatic hepatitis. On two occasions, administration of the drug was associated with a decrease of jaundice, pruritus, and serum bile acid levels. This strongly suggests that phenobarbital may be effective not only in intrahepatic cholestasis, as reported earlier, but also in extrahepatic obstruction, and therefore cannot be used for the differention of these two types of cholestasis.