A Validated Rp-hplc Method for Simultaneous Estimation of Amlodipine and Lisinopril in Pharmaceutical Dosage Form

A reverse phase high performance liquid chromatography (RP-HPLC) method for the simultaneous estimation of amlodipine and lisinopril in marketed formulation is developed. The determination was carried out on a Phenomenex C18 (250 x 4.6 mm, 5 μm) column using a mobile phase of 0.02 M phosphate buffer solution: methanol (75:25v/v, pH 7.0). The flow rate was 1.0ml/min with detection at 212 nm. The retention time for amlodipine was 4.11 min and for lisiopril 7.29 min. Amlodipine and Lisinopril showed a linear response in the concentration range of 10-110 μg/ml. The correlation coefficient (' r ' value) for amlodipine and lisinopril was 0.9991 and 0.9992, respectively. The results of analysis have been validated statistically and by recovery studies. The percentage recoveries obtained for amlodipine and lisinopril ranges from 100.04 to 100.57%. INTRODUCTION: Amlodipine (AMD) is chemically a 2[(2-Aminoethoxy)methyl]-4-(2-chlorophenyl)-1,4dihydro-6-methyl-3,5-pyridine dicarboxylic acid3ethyl 5-methyl ester and it belongs to the class of calcium channel blocker 1, . Several spectroscopic 3, , RP-HPLC , HPTLC , LC-MS/MS 8 and LC-MS 9 have been reported for the estimation of amlodipine individually and in combination with other drugs. Lisinopril(LSNP), (S)-1-[N2-(1-Carboxy-3-phenylpropyl) L-lysyl]-L-proline dihydrate is an angiotensin converting enzyme inhibitor that is used in the treatment of hypertension and heart failure . Various spectrophotometric methods have been reported for the determination of lisinopril in pharmaceutical tablets using different reagents . First and second derivative spectrophotometric 11, 12 and spectrofluorometric methods 11 were developed. The chromatographic techniques of analyses, HPLC , micellar electro kinetic chromatography 13 and gas liquid chromatography 14 have been reported for the estimation of lisinopril individually and in combination with other drugs. But no method is developed so far for the combination of AMD and LSN. A successful attempt is made to estimate the two drugs simultaneously. Therefore it was thought worthwhile to develop an accurate and rapid RP-HPLC method for simultaneous estimation of AMD and LSN from tablet formulations.