DEVELOPMENT AND VALIDATION OF RP-HPLC AND SPECTROPHOTOMETRIC METHOD FOR SIMULTANEOUS ESTIMATION OF ATORVASTATIN AND AMLODIPINE IN PHARMACEUTICAL DOSAGE FORMS

A simple, rapid, precise, accurate, sensitive and time consuming reverse phase high performance liquid chromatography (RP-HPLC) and spectrophotometric method for simultaneous estimation of atorvastatin and amlodipine in pharmaceutical dosage forms have been developed and validated. Drug was resolved on a C₁₈ column (Phenomenex phenyl hexyl column, 250mm_* 4.6mm i.d, 5um). Utilizing mobile phase of water with 0.4%v/v triethyl amine and acetonitrile with diluted orthophosphoric acid pH adjusted to 5.2 in a ratio of 52.5:47.5 of water and acetonitrile respectively. Mobile phase was delivered at the flow rate of 1.0ml/min. Ultraviolet detection was carried out at 229nm. Separation was completed within 7.75 minutes. Calibration curve was linear with correlation coefficient (r²)=0.999. Over a concentration range 5-25ug/ml, using diclofenac 10ug/ml as IS. Recovery was between 99.26, 100.2 percentage. In spectrophotometric method it involves the formation and solvation of simultaneous equation at 242nm for Atorvastatin and 256nmfor Amlodipine using Acetonitrile and Water (10:90) as mobile phase. The standard deviation was found to be less than 1% for the assay of tablet. The proposed methods were successfully employed for the estimation of Atorvastatin and Amlodipine in combined tablet formulation.