Stability-indicating method for the determination of assay and quantification of impurities in amlodipine–atorvastatin combination dosage form by RP-HPLC

Abstract

ABSTRACTA simple stability-indicating RP-HPLC method was developed and validated for quantification of amlodipine, atorvastatin, and its impurities on Waters HPLC using Unisol C18 5 µm, 250 × 4.6 mm column in their combined tablet dosage as per ICH guidelines. The gradient (T/%B) at 0/42, 18/42, 22/75, 30/75, 32/42, and 35/42 of 40 mM 4.7 pH ammonium acetate as mobile phase A and acetonitrile as mobile phase B of flow rate 1.5 mL/min and 240 nm wavelength. Peak purity compiled for amlodipine and atorvastatin in all stressed conditions. For impurities: Precision was found in between 1.5 and 3.6%. The limit of detection and quantification for amlodipine, amlodipine impurity A, and atorvastatin was found to be 0.06 and 0.18 µg/mL, for atorvastatin Impurity A, B, C, and H was determined as 0.04 and 0.11 µg/mL, for Atorvastatin Impurity D was measured as 0.11 and 0.28 µg/mL, respectively. The linear regression achieved >0.9999 from 0.22 to 7.5 µg/mL. Recovery was observed in between 97 and 101%. For assay: Precision was determined in between 0.1 and 0.2%. The linear regression achieved >0.9999 for amlodipine and atorvastatin. Recovery ranged from 100 to 101%. The validated method was found to be accurate, precise, reliable, and robust to determine the assay as well as impurities in amlodipine–atorvastatin combination dosage formulation.