Increased sulfobromophthalein clearance in a patient receiving phenobarbital and other anticonvulsant drugs.

A marked increase in bromosulfophthalein, dibromosulfophthalein, and indocyanine green fractional clearance was found in a patient who had received phenobarbital for 30 years and other anticonvulsant agents for 6 years. This was related to a marked increase in hepatic blood flow, while hepatic extraction remained normal. These changes were associated with signs of hepatic microsomal enzyme induction (in particular a 2-fold increase in liver bilirubin UDP-glucuronyltransferase activity and hypertrophy of the smooth endoplasmic reticulum in the hepatocytes). Drug administration (especially phenobarbital) should be considered as a possible cause of increased bromosulfophthalein clearance in man.