Absorption and disposition of [14C]-molsidomine in laboratory animals

14C-Labelled N-ethoxycarbonyl-3-morpholinosyndnonomine(14C-molsidomine, Corvaton) was administered orally to mouse, rat, rabbit, dog and rhesus monkey, and i.v. to rat and dog, at a dose level of 6 mg/kg-1. The rates and routes of excretion of radioactivity were determined. The oral dose was well-absorbed in all species and most (greater than 75%) of the radioactive dose was excreted in urine. In rat and dog less than 1% of the dose was present as expired 14CO2. In dog and rhesus monkey, small amounts of radioactivity were eliminated relatively slowly. In rat, dog and rhesus monkey, the three species examined in detail, radioactivity was generally distributed throughout the body 4-10 days after dosing. Levels were highest in liver, pelt, blood and the gastrointestinal tract. Whole-body autoradiographic studies in rat and rhesus monkey showed that at 4 days post-dose, radioactivity was highest in stomach wall and was distributed into other tissues in lesser amounts. In view of its mode of action, it was interesting that radioactivity was also associated with the heart muscle and aorta walls.