[Studies on the biotransformation of 5-vinyl-5-(1-methylbutyl)- and 5-vinyl-5-(1-ethyl-propyl)-barbituric acid (author's transl)].

After taking 5-vinyl-5-(1-methylbutyl)-barbituric acid (vinylbital, Speda) another not yet known metabolite (Sp 1) was isolated from urine and was identified as 5-vinyl-5-(1-methyl-3-carboxy-propyl)-bartiburic acid. Compound Sp 2a is 1-methylhydantoin. Presumably this compound is an artifact from creatinine. We have not yet been able to identify a third mercury(I)-nitrate-positive substance Sp 2b. The supposition that this compound were a metabolite of 5-vinyl-5-(1-ethyl-propyl)-barbituric acid could not be upheld. The three mercury(I)-nitrate-positive substances appearing in the urine after taking 5-vinyl-5-(1-ethyl-propyl)-barbituric acid, behaved in chromatographic analysis completely differently from the unknown compound Sp 2b. The substances were isolated. Two of them are the metabolites 5-vinyl-5-(1-ethyl-2-carboxy-ethyl)-barbituric acid and 5-(1-ethyl-propyl)-barbituric acid. We are not sure whether the third compound identified as 5-hydroxy-5-(1-ethyl-propyl)-barbituric acid, is formed in vivo, as the substance could have developed by oxidation or by the influence of peroxide contained in ether, as well. A product hydroxylized in the side chain, like in vinylbital, was not found in the metabolite urine of 5-vinyl-5-(1-ethyl-propyl)-barbituric acid.