title: Multiple inverse isotope dilution assay for oxprenolol and nine metabolites in biological fluids.
abstract: An isotope dilution assay for the specific determination of 14C-labelled oxprenolol and nine of its metabolites in the same biological sample is described. After addition of unlabelled carriers to the sample, oxprenolol and the metabolites were isolated by base- and acid-specific extraction and separated by normal-phase high-performance liquid chromatography using two different mobile phases. Quantitation of the various peaks was performed by on-line ultraviolet detection at 275 nm and off-line radiometry by liquid scintillation counting. Endogenous compounds and unknown metabolites did not interfere in the assay. The analysis of rat and dog blood, plasma and urine samples spiked with [14C]oxprenolol hydrochloride, showed mean recoveries between 98.7 and 99.8%. The assay was used to investigate the metabolic fate of [14C]oxprenolol in the dog. Analyses of blood and urine demonstrated the quantitative significance of the various metabolites in the biotransformation of oxprenolol.
mesh_terms: D000818:Animals; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D004285:Dogs; D008297:Male; D010096:Oxprenolol / Q000097:blood / Q000378:metabolism* / Q000652:urine; D011865:Radioisotope Dilution Technique; D051381:Rats
chemical_list: D010096:Oxprenolol