Isolation, identification and in vitro synthesis of conjugates of penbutolol and its metabolites.

The metabolites of 1-tert.-butylamino-3-(2-cyclopentylphenoxy)propan-2-ol (penbutolol Betapressin) penbutolol 2-glucuronide, 4'-OH-penbutolol 2-glucuronide, 4'-OH-penbutolol 4'-sulfate and 1''-dehydropenbutolol 2-glucuronide were isolated from the urine of patients, purified by high-performance liquid chromatography and characterised by 1H-NMR and mass spectroscopy. Penbutolol 2-glucuronide and 4'-OH-penbutolol 4'-glucuronide were synthesised in vitro from penbutolol and 4'-OH-penbutolol, respectively, using glucuronyltransferase.