Improved Ultra-Performance LC Determination of Indapamide in Human Plasma

A simple, rapid, sensitive and selective method for the analysis of indapamide in human plasma, utilizing ultra performance liquid chromatography (UPLC), has been developed and validated to satisfy FDA guidelines for bioanalytical methods. The analyte and the internal standard, sulfamethazine, were isolated from plasma samples by liquid–liquid extraction with diethyl ether. Separation was performed with an Acquity C18 column. The gradient composition of mobile phase was composed of acetonitrile and sodium dihydrogenphosphate buffer (adjusted to pH 3.33 with 85% o-phosphoric acid) at a flow rate of 0.5 mL min⁻¹. The assay exhibited a linear dynamic range of 1–100 ng mL⁻¹ for indapamide in human plasma. The limit of quantification (LOQ) was 1 ng mL⁻¹. The method was successfully applied to the pharmacokinetic and bioequivalence studies of indapamide formulations.