Utilization of 1,2-Naphthoquine-4-Sulfonate (NQS) for Development and Validation of Stability indicating HPLC method for the Simultaneous Analysis of Amlodipine, Hydrochlorothiazide and Valsartan in Pharmaceutical Formulation

A simple, specific, accurate and precise, stability indicating HPLC method for the simultaneous determination of antihypertensive drug combination consisting of amlodipine (AML), hydrochlorothiazide (HCT) and valsartan (VAL) was developed and validated. The proposed method is based on the derivatization of drugs with 1,2-naphthoquinone-4-sulfonic (NQS). The optimized conditions for the separation of the three analytes was consisted of ODS C-18 (150 mm × 4.6 mm i.d. 5 μm) column, mobile phase: acetonitrile-potassium dihydrogen phosphate pH 3.5- acetonitrile (45:55 % v/v). Column temperature was maintained at 40°C; Flow rate: 1.5 mL/min; detection: 460 nm; and injection of 20μL. The precision of the method was shown through adequate repeatability or intraday precision (RSD ≤ 2) and interday precision (RSD ≤ 2). The method demonstrated adequate linearity of detector response over the range (2 - 30) μg/mL for AML, (2.5 - 30) μg/ mL for HCT and (32 - 224). μg /mL for VAL. The limits of detection for AML, HCT and VAL were 0.02, 0.02 and 0.01 µg/mL, while the limits of quantification were 0.05, 0.07 and 0.04 µg/mL respectively. The method also showed adequate robustness to variations in mobile phase, pH, and column temperature, reaction time and reagent concentrations. The full recoveries of each working standard for all compounds were within ICH specifications of 98-101% which showed that the method was accurate. The proposed method proved to be stability indicating by resolution of the analytes from their accelerated storage conditions products. The developed method is rapid (run time 5 min), selective, requires simple sample preparation procedures and simple mobile phase combinations. It is also cost effective and represents a good procedure for determination of AML, HCT and VAL with NQS in bulk raw materials and pharmaceutical dosage forms.