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 (r) =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. INTRODUCTION: Atorvastatin (fig-I) is chemically [R(R*, R*0] [R-(R*, R*0] -2-(4-Fluorophenyl), dehydroxy5(1-mehtylethyl)3phenyl-4[9phenyl amino)-carbonyl]-1H-pyrrole-1-heptanoic acid. Lipid lowering agent. Amlodipine (Fig. 1) is chemically 2-[(2Aminoethoxy)methyl]-4-(2-chlorophenyl)-1, 4-dihydro6-methyl-3, 5-pyridinedicarboxylic acid 3-ethyl 5methyl ester act as a calcium channel blocker . ATORVASTATIN AMLODIPINE FIGURE 1: STRUCTURE OF ATORVASTATIN AND AMLODIPINE MATERIALS AND REAGENTS: Atorvastatin and Amlodipine standards were obtained from Zydus Medica Laboratories, Ltd. (Ahmedabad, India), methanol, acetonitrile and buffer (HPLC grade) were obtained from Qualigens Fine Chemicals (Mumbai, India). The (A) tablets (Zydus Medica laboratories) of