Metabolic Fate of 5-Ethoxycarbonyl-3-Morpholinosydnonimine (Sin-10)

5-Ethoxycarbonyl-3-morpholinosydnonimine (SIN-10), synthesized by Masuda et al. (1) is one of sydnonimine derivatives with mesoionic ring. Following is itschemical structure. The pharmacological studies on SIN-10 by Takenaka et al. (2) showed a sustained hypotensive effect in rabbits. The similar effect was also confirmed in the dog, cat and rat by Kikuchi et al. (3). In order to provide a biochemical basis for the pharmacological and toxicological mechanisms, the metabolic aspects of SIN-10 have been studied in rats and mice. The present paper deals with the absorption, excretion and tissue distribution of 14C-labeled SIN-10. The metabolic conversion in the living matters and the identification of the metabolites are reported elsewhere (4).