RADIOCHEMICALLY PURE [1-C-14] VALPROIC ACID - A MIXTURE OF LABELED STRUCTURAL ISOMERS

Abstract

Ongoing studies of the disposition of valproic acid (VPA) and its glucuronide conjugate required the radiolabeled drug for greater sensitivity and tracing of oxidation metabolites. [1-14C]VPA hereinafter called LABEL (radiochemical purity greater than 98% as determined by paper and thin layer chromatography) was purchased from Amersham International, U.K. Quantitative analysis of VPA and VPA-glucuronide in bile and urine samples from rats given VPA and tracer LABEL by our standard gas chromatographic assay showed gross discrepancies with the results obtained by liquid scintillation counting of the same extracts. Examination of the purity of LABEL was therefore undertaken. Equilibration of LA..