The fate of drotaverine-acephyllinate in rat and man. I. Absorption, distribution and excretion in the rat.

Two different labelled forms were used for the pharmacokinetic investigations: the carbon 1 in the isoquinoline ring (Drotaverine-14C-Acephyllinate) and the carboxyl group of theophylline-7-acetic acid (Drotaverine-Acephylline-14C-ate). Drotaverine-14C-Acephyllinate was rapidly absorbed from duodenal and ileal segments. Biliary excretion was substantial after oral administration and radioactivity was excreted mostly in the feces. Absorption of Drotavenine-Acephylline-14-C-ate from the gastrointestinal tract was very poor and radioactivity was therefore excreted for the most part in the feces. The results of the study were confirmed by whole body autoradiography.