Gemfibrozil--the effect of biliary cholesterol saturation of a new lipid-lowering agent and its comparison with clofibrate.

Clofibrate is known to increase cholesterol saturation of bile and the prevalence of gallstones. We studied 10 healthy volunteer subjects to determine the effect of gemfibrozil (a new lipid-lowering agent) on biliary cholesterol saturation and to compare it with that of clofibrate. Biliary cholesterol saturation indices were calculated on fasting duodenal bile samples collected before and after administration of each drug for 4 weeks using a 4-week "washout" period between each preparation. There was a statistically significant rise in the cholesterol saturation index from a control value, taken as the mean of 2 samples, of 1.226 (0.785--1.526), median (range), to 1.547 (0.807--1.781) after clofibrate, P less than 0.05, but the rise to 1.352 (0.840--2.686) after gemfibrozil was not significant. However, direct comparison of the cholesterol saturation indices on clofibrate and gemfibrozil revealed no statistically significant difference. Only prospective clinical trials will establish definitively the risk of cholelithiasis on gemfibrozil but these results suggest that this drug is unlikely to have an advantage over clofibrate in this respect.