Metabolism of quinalbarbitone.

The human metabolism of (+/-)-5-allyl-5-(1'-methylbutyl) barbituric acid (I), quinalbarbitone, taken orally, has been studied. Comparison of g.c. and g.c.-m.s. data from derivatized extracts of urine with similar data from synthetic samples confirmed the presence of the two diastereoisomeric forms of 5-allyl-5-(3'hydroxy-1'-methylbutyl)barbituric acid (II), 5-allyl-5-(3'-oxo-1'-methylbutyl)barbituric acid (III), 5-allyl-5-(1'-methyl-3'-carboxypropyl)barbituric acid (IV), and 5-(2',3'-dihydroxypropyl)-5-(1'-methylbutyl)barbituric acid (V) in the urine. There was no evidence for the urinary excretion of unchanged drug. The rate of excretion of these metabolites has been examined in some detail, and rate-limited kinetics shown to apply for excretion of the acid (IV) and the diol (V).