QUANTITATIVE ANALYTICAL METHODS FOR THE DETERMINATION OF A NEW HYPERTENSION DRUG, CGS-25462, AND ITS METABOLITES (CGS 25659 AND CGS-24592) IN HUMAN PLASMA BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Two simple and sensitive reversed-phase high-performance liquid chroma tography (HPLC) methods were developed and validated for the quantitat ive determination of a novel hypertension drug CGS 25462 and its major metabolites CGS 24592 and CGS 25659 in human plasma. CGS 25462 and CG S 25798 (internal standard) were purified by one-step liquid-liquid ex traction with methylene chloride. The metabolites were analyzed on HPL C after plasma protein precipitation with 10% trichloroacetic acid (TC A). Separations were achieved on a Zorbax RX C-18 column. All compound s were detected by using a fluorescence detector. The excitation wavel ength was 254 nm, and emission was monitored at 325+/-12.5 nm. Assessm ent of recovery and reproducibility indicated good accuracy and precis ion. Over the validation concentration range of 10 to 1000 ng/ml for C GS 25462 and 25 to 5000 ng/ml for both metabolites, overall mean relat ive recoveries were 96% for CGS 25462, 101% for CGS 25659 and 107% for CGS 24592, and the coefficients of variation were 4.6 to 13% for CGS 25462, 9.5 to 13% for CGS 25659 and 7.7 to 15% for CGS 24592. The limi ts of quantification (LOQs) were 10 ng/ml for CGS 25462 and 25 ng/ml f or CGS 24592 and CGS 25659, which were of sufficient sensitivity to me asure the concentrations of CGS 25462, CGS 25659 and CGS 24592 in plas ma samples from normal volunteers following a single 800 mg oral dose. (C) 1998 Published by Elsevier Science B.V.