DETERMINATION OF CISAPRIDE AND NORCISAPRIDE IN HUMAN PLASMA USING HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ULTRAVIOLET DETECTION

A simple, rapid and reproducible high-performance liquid chromatograph ic assay for cisapride and norcisapride in human plasma is described. Samples of plasma (150 mu l) were extracted using a C-18 solid-phase c artridge. Regenerated tubes were eluted with 1.0 ml of methanol, dried , redissolved in 150 mu l of methanol and injected. Chromatography was performed at room temperature by pumping acetonitrile-methanol-0.015 M phosphate buffer pH 2.2-2.3 (680:194:126, v/v/v) at 0.8 ml/min throu gh a C-18 reversed-phase column. Cisapride, norcisapride and internal standard were detected by absorbance at 276 nm and were eluted at 4.3, 5.3 and 8.1 min, respectively. Calibration plots in plasma were linea r (r>0.998) from 10 to 150 ng/ml. Intraday precisions for cisapride an d norcisapride were 3.3% and 5.4%, respectively. Interday precisions f or cisapride and norcisapride were 9.6% and 9.0%, respectively. Drugs used which might be coadministered were tested for interference. (C) 1 998 Elsevier Science B.V. All rights reserved.