High-performance liquid chromatography with chemiluminescence detection ofpenbutolol and its hydroxylated metabolite in rat plasma

This paper describes a new method of high-performance liquid chromatography with chemiluminescence detection for the analysis of penbutolol (PB) and i ts main metabolite, 4-hydroxy penbutolol (4-OH PB) in rat plasma. 4-Dimethy laminosulfonyl-7-(N-chloroformylmethyl-N-methyl) amino-2,1,3-benzoxadiazole (DBD-COCl) was used as a fluorogenic labeling reagent. A mixture of hydrog en peroxide and bis[4-nitro-2-(3,6,9- trioxadecyloxycarbonyl)phenyl]oxalate (TDPO) in acetonitrile was used as a post-column chemiluminogenic reagent. The derivatives of PB and 4-OH PB with DBD-COCl were separated by isocrati c effluent with 0.01 M imidazole buffer (pH 7.0)-acetonitrile within 10 min . The detection limits of the proposed method for PB and 4-OH PB were 9.9 a nd 15 fmol on column, respectively. After intravenous administration of PB in rats, its plasma concentration profiles of PB and 4-OH PB were determine d by the proposed method. PB was demonstrated to be rapidly metabolized to 4-OH PB at the same rate as cardiac output. (C) 2001 Elsevier Science B.V. All rights reserved.