Tissue distribution of the novel antitussive compound vadocaine hydrochloride in white female mice studied by whole-body autoradiography.

The tissue distribution of tritium-labelled vadocaine hydrochloride (2',4'-dimethyl-6'-methoxy-3-(2-methylpiperidyl)propionanilide+ ++ hydrochloride, OR K-242-HCl; INN: vadocaine) was studied in female mice by whole-body autoradiography at different times (15 min - 24 h) after intravenous injection. Radioactivity disappeared rapidly from blood and was fairly selectively localized in the liver, the gall bladder and the intestinal contents. Vadocaine is evidently metabolized in the liver and a remarkable part of the drug and its metabolites are excreted into the bile. Accumulation of radioactivity in the kidneys shows that also renal elimination is important. A considerable accumulation into the lungs supports the peripheral anaesthetizing mechanism in the antitussive action of vadocaine. No detectable penetration into the brain was seen. At 24 h, only traces of the radioactivity could be detected in the liver and lungs.