Metabolism of beclamide after a single oral dose in man: quantitative studies

A simple reverse phase HPLC assay is described for the determination of the anticonvulsant compound, beclamide and its 3- and 4-hydroxyphenyl metabolites in urine. Following oral administration of 1 g beclamide to a panel of healthy volunteers, less than 0.4% of the dose was excreted unchanged in the 24-h urine and unconjugated 3- and 4-hydroxyphenyl metabolites were not detected. Based on examination of the urine after incubation with beta-glucuronidase and aryl sulphatase, it was found that these hydroxyl metabolites were excreted as both glucuronide and sulphate conjugates. For each metabolite the glucuronide was the major excretory product (approximately 10:1). The 24-h excretion of the combined conjugated metabolites was 7% (for the 3-hydroxy metabolite) and 24% (for the 4-hydroxy metabolite) of the dose. Approximately 22% of the administered dose of beclamide was excreted as hippuric acid. In view of the simplicity of assay, beclamide may be a useful tool substance with which to examine factors influencing the xenobiotic metabolic pathways of benzene ring hydroxylation and glucuronide and sulphate conjugation in man.