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Updated: Oct 7, 2026

High-throughput and Comprehensive Drug Surveillance Using Multisegment Injection-Capillary Electrophoresis-Mass Spectrometry
Published on: April 23, 2019
Determination of clozapine and its N-desmethyl metabolite by high-performance liquid chromatography with ultraviolet
A Llerena1, R Berecz, M J Norberto
1Department of Pharmacology and Psychiatry, Faculty of Medicine, University of Extremadura, Badajoz, Spain. allerena@unex.es
Abstract:
A rapid high-performance liquid chromatographic method has been developed for the simultaneous determination of the atypical antipsychotic drug clozapine and its principal metabolite, N-desmethyl clozapine in human plasma. After liquid-liquid extraction the compounds were separated in a reversed-phase column and measured by ultraviolet absorption at 230 nm. For both compounds inter-day variations were <3.8%, and, based on a plasma sample volume of 2 ml, the limits of quantification were 25 ng/ml. Analytical interference from coadministered psychoactive drugs and their metabolites was also studied, and no interference was found from the most commonly used antidepressants and antipsychotic drugs. The assay is sufficiently sensitive and easy to use for the analysis of plasma samples in human clinical trials and therapeutic drug monitoring.

