Abstract
The excretion rate of metabolites was investigated in vivo after the administration of cyclobarbital, hexobarbital, and methylbarbital in rabbit. It was found that cyclobarbital was easily oxidized in the cyclohexenyl group and completely excreted within 10 hours. In the case of methylbarbital, the excretion of barbital, the demethylated compound, was slow but significant. Based on the results of in vitro studies it was shown that liver slice was capable of demethylating hexobarbital and methylbarbital, but that of kidneys was not. Moreover, the production of 3-keto-nor-MHB was observed only when 3-keto or 3-OH-MHB was used as the substrate. Therefore, hexobarbital seemed to be first oxidized in the cyclohexenyl group and then demethylated.
