Background: Although it has been shown that chronic administration of ursodeoxycholic acid increases gallbladder fasting and residual volume, it is unknown whether ursodeoxycholic acid exerts an acute effect on gallbladder volume. We therefore evaluated the effect of a single oral dose of ursodeoxycholic acid on gallbladder volume in healthy volunteers.
Methods: After the volunteers had fasted overnight, gallbladder volume was measured sonographically every 15 min for 5 h. Following a 1-h control period group I (n = 8) received ursodeoxycholic acid (1000 mg) orally with 100 ml of water, whereas group II (n = 8) received 100 ml of water (placebo) only. Gallbladder volumes were calculated, applying the sum-of-cylinders method. Serum levels of ursodeoxycholic acid were determined by gas chromatography at 1-h intervals.
Results: Gallbladder fasting volumes before ursodeoxycholic acid were similar in both groups (24.0 +/- 2.3 ml versus 25.4 +/- 3.3 ml; NS). After ingestion of ursodeoxycholic acid (group I) gallbladder volume increased rapidly, reaching 27.6 +/- 3.1 ml (p < 0.04) 1 h and 38.4 +/- 3.4 ml (p < 0.02) 4 h after ingestion of ursodeoxycholic acid. The individual gallbladder volumes after ingestion of ursodeoxycholic acid in group I increased to 146%-211% of pretreatment values. Ursodeoxycholic acid serum levels increased from 0.94 +/- 0.38 mumol/l to 10.51 +/- 1.36 mumol/l (p < 0.001) and correlated closely with gallbladder volumes (r = 0.80; p < 0.05). After ingestion of water only (group II) gallbladder volume decreased transiently from 15 min to 30 min after water intake and then remained at pretreatment values throughout the study period.
Conclusion: Administration of a single oral dose of ursodeoxycholic acid causes a rapid increase in gallbladder volume, which reaches 163 +/- 10% of pretreatment volume at 4 h and is closely correlated with ursodeoxycholic acid serum levels.