Determination of a new antihypertensive agent (2R,4R)-2-(2-hydroxyphenyl)-3-(3-mercaptopropionyl)-4- thiazolidinecarboxylic acid in blood by high-performance liquid chromatography with electrochemical detection.

A sensitive method has been developed for the determination of a new antihypertensive agent, (2R,4R)-2-(2-hydroxyphenyl)-3-(3-mercaptopropionyl)-4-thiazolidinecar boxylic acid (I), in human blood. Because the drug is unstable in biological fluids, it was immediately derivatized by treating the freshly drawn blood specimens with N-(4-anilinophenyl)maleimide. The adduct was separated and determined by high-performance liquid chromatography with electrochemical detection on a reverse-phase column. The assay method was satisfactory with respect to the sensitivity and precision, providing a quantitation limit of 2 ng/ml and coefficient of variation of 3%. Preliminary pharmacokinetic data were obtained by orally administering I to two patients with essential hypertension.