Abstract
The pharmacological actions of S-carbethoxythiamine, S-carbobutoxythiamine and O, S-dicarbethoxythiamine in experimental animals were compared with those of thiamine-HCl. Toxic symptoms of these CATs, except for those of DCET, in mice were almost the same as those of thiamine-HCl. The toxicity of these compounds in mice decreased in the following order : thiamine-HCl, DCET, CBT, and CET. In cats a marked fall of blood pressure, respiratory depression, and relaxation of the intestine were observed by the intravenous administration of large doses of the compounds. In such high doses these compounds also caused the depression of spontaneous movements of isolated rabbit hearts and isolated guinea pig auricles. In addition it seemed that the functions of striated muscles, as well as those of smooth muscles, were markedly lowered by the administration of the compounds in a dose of 10^<-3>. The action mechanisms of these compounds in relation to pharmacological effects were further discussed.
