Urinary metabolites of pinacidil: I. Isolation and identification of the metabolites in rat urine.

1. The urinary metabolites of pinacidil administered orally to rats, were analysed by h.p.l.c. Seven metabolites were isolated from rat urine following fractionation on an HP-20 column and purified by t.l.c. 2. The major metabolite was pinacidil-pyridine-N-oxide (M-1). omega-Hydroxypinacidil (M-2) and dealkylpinacidil (M-3) were less abundant metabolites, and minor metabolites were the M-2-aldehyde, in which an intramolecular ring had formed (M-4), M-2-pyridine-N-oxide (M-5), carbamoyl-pinacidil (M-7) and M-7-pyridine-N-oxide (M-6). 3. Metabolic pathways of pinacidil in rats were postulated from the isolated metabolites.