Sensitive high-performance liquid chromatographic determination of chlorzoxazone and 6-hydroxychlorzoxazone in plasma.
A rapid and sensitive high-performance liquid chromatographic assay was developed for the quantitation of chlorzoxazone and its major metabolite 6-hydroxychlorozoxazone in plasma. These compounds, as well as the internal standard 5-fluorobenzoxazolone, were extracted from plasma (0.5 ml) using C18 solid-phase extraction columns. The extracts were analyzed on a 10-microns Waters C18 muBond-apak column with a mobile phase of acetonitrile-tetrahydrofuran-0.1 M ammonium acetate (22.5:5.5:72). The assay utilized ultraviolet detection (283 nm) which provided sensitivity and specificity sufficient to simultaneously quantify > or = 100 ng/ml chlorozoxazone and 6-hydroxychlorzoxazone in plasma. The mean correlation coefficient of the multi-level standard curves for each compound was 0.996 or greater over a concentration range of 100-3000 ng/ml. The inter-day and intra-day coefficients of variation were < 6%. This method has been used by our laboratory to provide the unattended overnight analysis of chlorozoxazone and 6-hydroxychlorzoxazone in plasma samples obtained from human study subjects.
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Department of Pharmacy and Therapeutics, School of Pharmacy, University of Pittsburgh Medical Center, PA 15261.
Frye
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D002138:Calibration; D002753:Chlorzoxazone / Q000031:analogs & derivatives* / Q000097:blood* / Q000493:pharmacokinetics; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004355:Drug Stability; D006801:Humans; D015203:Reproducibility of Results; D013056:Spectrophotometry, Ultraviolet
C039289:6-hydroxychlorzoxazone; D002753:Chlorzoxazone