[Bile acid-independent effect of hymecromone on bile secretion and common bile duct motility]

Hymecromone (4-methyl-umbiliferone) has been used for more than 20 years for the treatment of functional and obstructive spasms of the biliary tract. Its mode of action however is still largely unknown. We investigated the effect of 4-methyl-umbiliferone p. o. and i. v. on gall bladder and common bile duct motility and studied potentially indirect effects via alterations in bile acid metabolism.

Twenty healthy volunteers, aged 25 - 37, 10 males, 10 females, were included into a Placebo-controlled, randomised, cross-over double-blind study. Subjects were treated with 800 mg hymecromone p. o.; in addition a standardized meal (Biloptin, 40 gs) was given. Gall bladder volume and common bile duct diameter were determined by ultrasound. Conjugated and unconjugated bile acids were analysed by gas chromatography. Additionally, in a third open label phase hymecromone was given i. v.

Common bile duct diameter was significantly larger after a standard meal with hymecromone given p. o. or i. v. than with placebo (each p < 0.01). However, alterations in gall bladder volume after a standard meal were not different between placebo and hymecromone (p. o. or i. v.). Unconjugated and conjugated bile acids rose after standard meal in all three groups without significant differences between hymecromone and placebo.

Hymecromone was associated with significant dilation of the common bile duct. In contrast to previous reports an effect of hymecromone on gall bladder motility could not be observed. The unchanged values of bile acids in serum after hymecromone compared to placebo, together with the dilatation of the common bile duct after hymecromone, may indicate a bile acid-independent effect of hymecromone on bile secretion.