Clonazepam quantification in human plasma by high-performance liquid chromatography coupled with electrospray tandem mass spectrometry in a bioequivalence study.

Author(s): Cavedal LE, Mendes FD, Domingues CC, Patni AK, Monif T, Reyar S, Pereira Ados S, Mendes GD, De Nucci G

Affiliation(s): Department of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas/SP, Brazil.

Publication date & source: 2007-01, J Mass Spectrom., 42(1):81-8.

Publication type: Randomized Controlled Trial; Research Support, Non-U.S. Gov't

A rapid, sensitive and specific method for quantifying clonazepam in human plasma using diazepam as the internal standard (IS) is described. The analyte and the IS were extracted from plasma by liquid-liquid extraction using a hexane/diethylether (20 : 80, v/v) solution. The extracts were analysed by high-performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC-MS-MS). Chromatography was performed on a Jones Genesis C8 4 microm analytical column (100 x 2.1 mm i.d.). The method had a chromatographic run time of 3.0 min and a linear calibration curve over the range 0.5-50 ng/ml (r2 > 0.9965). The limit of quantification was 0.5 ng/ml. This HPLC/MS/MS procedure was used to assess the bioequivalence of two clonazepam 2 mg tablet formulations (clonazepam test formulation from Ranbaxy Laboratories Ltd and Rivotril from Roche Laboratorios Ltda as standard reference formulation). Copyright 2006 John Wiley & Sons, Ltd.