Metabolism and time-course excretion of murideoxycholic acid, a 6β-hydroxylated bile acid, in humans

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The metabolism and time-courses of urinary and fecal excretions of murideoxycholic acid (MDCA; 3 alpha,6 beta-dihydroxy-5 beta-cholanoic acid), a 6 beta-hydroxylated bile acid, was investigated in man. The study was carried out in two groups of subjects. Six cholecystectomized patients fitted with a cystic duct drain ingested 100 mg of a tracer dose of 3H-MDCA. Time-course of radioactivity in plasma was then followed for an 8-h period. Biliary, urinary and fecal excretions of radioactivity were measured for a 5-day period and excreted MDCA metabolites were identified. Five lithiasic patients with intact enterohepatic circulation ingested 500 mg of the same tracer dose of 3H-MDCA. Radioactivity in plasma was followed for a 49-h period and urinary and fecal excretions of radioactivity were measured daily for 7 days. In the first group, the excretion of the radioactivity by the three routes (bile+urine+feces) reached 97.8 +/- 1.5% of the ingested dose but dropped to 75 +/- 8.3% (urine+feces) in patients in the second group. In cholecystectomized patients, the estimation of intestinal MDCA absorption was dependent on cystic duct drain flow rate and gave values ranging from 20% to 87%. The biological half-life of MDCA in lithiasic patients averaged 3.4 +/- 0.7 days. Radioactivity appeared in the plasma in the first hour and reached a maximum 6 and 3 h after the beginning of the experiment in group I and II respectively. In the second group, another peak of radioactivity in plasma was observed just after breakfast.(ABSTRACT TRUNCATED AT 250 WORDS)