[Metabolism of meproscillarin in man (author's transl)]

The investigations on the metabolism of 14-Hydroxy-3beta-[(4-O-methyl-alpha-L-rhamnopyranosyl)oxy]-14beta-bufa-4,20,22-trienolide (meproscillarin, Clift) were performed in 5 healthy test persons as well as in 4 patients with biliary fistula, applying a single oral dose of 0.5 mg of 3H-meproscillarin. The elimination half-life of total plasma radioactivity was about 51 h in the test persons, and 18 and 30 h in the patients whose bile was drawn off via a T-drain. The test persons excreted about 20% of total radioactivity renally and about 56% with the faeces. The patients excreted between 29% and 89% of the radioactive dose applied with the bile, the major part being eliminated already after 24 h. Up to 3% was excreted with the faeces. Renal excretion varied between 6% and 22%. Total radioactivity in plasma, bile, urine and faeces was separated into chloroform-soluble and chloroform-insoluble fractions, which were further differentiated by thin-layer chromatography. Whereas in plasma, bile and urine mainly chloroform-insoluble metabolites of meproscillarin were present, the chloroform-soluble fraction in the faeces represented the major portion, also containing primarily meproscillarin. The results are discussed.