Determination of clozapine, desmethylclozapine and clozapine N-oxide in human plasma by reversed-phase high-performance liquid chromatography with ultraviolet detection

摘要: An isocratic high-performance liquid chromatography (HPLC) method with ultraviolet detection for the simultaneous determination of clozapine and its two major metabolites in human plasma is described. Analytes are concentrated from alkaline by liquid–liquid extraction n-hexane–isoamyl alcohol (75:25, v/v). The organic phase back-extracted 150 μl 0.1 M dibasic phosphate (pH 2.2 25% H3PO4). Triprolidine used as internal standard. For chromatographic separation mobile consisted acetonitrile–0.06 buffer, pH 2.7 phosphoric acid (48:52, eluted at a flow-rate 1.0 ml/min, separated on 250×4.60 mm I.D. analytical column packed 5 μm C6 silica particles, measured UV absorbance 254 nm. requires 7 min. Calibration curves three analytes linear within clinical concentration range. Mean recoveries were 92.7% clozapine, 82.0% desmethylclozapine 70.4% N-oxide. C.V. values intra- inter-day variabilities ≤13.8% concentrations between 50 1000 ng/ml. Accuracy, expressed percentage error, ranged −19.8 to 2.8%. was specific sensitive quantitation limits 2 ng/ml both Among various psychotropic drugs their metabolites, only 2-hydroxydesipramine caused significant interference. applicable pharmacokinetic studies therapeutic drug monitoring.