Liu YY, van Troostwijk LJ, Guchelaar HJ. Simultaneous determination of clozapine, norclozapine and clozapine-N-oxide in human plasma by high-performance liquid chromatography with ultraviolet detection.
Biomed Chromatogr 2001;
15:280-6. [PMID:
11438972 DOI:
10.1002/bmc.73]
[Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A reversed-phase high-performance liquid chromatographic (HPLC) method for the simultaneous determination of clozapine and its two major metabolites, norclozapine and clozapine-N-oxide in human plasma has been developed and validated. The isocratic HPLC assay uses a mobile phase consisting of an acetonitril-buffered aqueous solution containing 146 microL of triethylamine and 200 microL of 85% phosphoric acid, adjusted to pH 3.3 with 10% potassiumhydroxide solution (400:600, v/v) at a flow-rate of 0.8 ml/min and a Lichrospher 100 RP-18 reversed-phase column and UV detection at 215 nm. Doxepine was used as the internal standard. Mean recoveries for clozapine, norclozapine, clozapine-N-oxide and doxepine were 95%, 98%, 96% and 94%, respectively, whereas the respective mean repeatability coefficients of variation were 3.4%, 2.7%, 4.3% and 0.9%. Reproducibility coefficients of variation were 1.3%, 1.8%, 3.6% and 0.5%, respectively. The mean correlation coefficient for the linear calibration curve (n = 2) for clozapine and norclozapine at a concentration range of 100-1600 ng/mL was 0.9998 and 0.9997, respectively; for clozapine-N-oxide (20-200 ng/mL) it was found to be 0.9986. The lower limits of quantitation were 12.5 ng/mL, 10 ng/mL and 12.5 ng/mL for clozapine, norclozapine and clozapine-N-oxide, respectively.
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