Effect of cimetidine on the metabolism of cholephilic dyes in Gilbert's syndrome.

The metabolism of indocyanine green, bromsulphophthalein and bilirubin was studied before and after a treatment for 2 weeks with cimetidine 1.0 g/day in 12 subjects with Gilbert's syndrome. There was no effect on the plasma clearance of indocyanine green and bromsulphophthalein, on the maximal biliary excretion capacity of bromsulphophthalein, on serum bilirubin concentrations or on the biliary metabolites of bromsulphophthalein and bilirubin. It is concluded that in Gilbert's syndrome two weeks of treatment with cimetidine had no effect on liver blood flow or on conjugation mechanisms which were independent of cytochrome P450.