Quantification of Amlodipine and Indapamide in Human Plasma by HPLC

A simple, sensitive, and selective HPLC method was developed and validated for the simultaneous estimation of Amlodipine besylate (AML) and Indapamide (IND) in human plasma for application in pharmacokinetic, bioequivalence, and bioavailability studies. AML, a calcium channel blocker, and IND, a thiazide-like diuretic, are widely prescribed in combination for hypertension management. The method employed liquid-liquid extraction using diethyl ether and dichloromethane, followed by chromatographic separation on a C18 column with a methanol-octane sulfonic acid mobile phase (79:21 v/v) at a flow rate of 1.2 mL/min and UV detection at 240 nm. The retention times for AML, IND, and the internal standard (carbamazepine) were 8.9, 2.9, and 3.6 min respectively. The method was linear over 0.075-15 ng/mL for AML and 0.3-60 ng/mL for IND, with correlation coefficients ¿0.998. Validation as per USFDA guidelines demonstrated accuracy, precision, recovery, stability, and selectivity within acceptance criteria. This validated HPLC method is robust and suitable for routine analysis of AML and IND in plasma, supporting clinical and regulatory studies.