In female Wistar rats, epomediol (Clesidren) (30-300 mg/kg p.o.) induced a dose-dependent increase of bile flow and a concomitant enhancement in both unchanged drug and its mono-beta-glucuronide (M 3) biliary levels. Pretreatment with galactosamine (300 mg/kg i.p.) abolished the bile flow increase and resulted in a marked decrease of M 3 but not of the unchanged drug. Moreover, a highly significant correlation (r = 0.809) between M 3 biliary concentration and bile flow was found.