DEVELOPMENT AND VALIDATION OF RPHPLC METHOD FOR SIMULTANEOUS ESTIMATION OF AMLODIPINE BESYLATE AND BENAZEPRIL HCL IN TABLET DOSAGE FORM Research Article

A simple, selective and rapid reversed phase high performance liquid chromatographic (RP-HPLC) method for the analysis of Benzapril and Amlodipine in tablet has been developed and validated. The chromatographic separation was achieved on (Inertsil ODS, 250 x 4.6mm, 5μ column) analytical column. The separation was achieved from C18 column at ambient temperature with a mobile phase consisting of methanol-acetonitrile buffer (solution of ammonium acetate and sodium pentanesulphonate ratio, 55:10:35 v/v, PH=3.00 adjusted with phosphoric acid) at a flow rate of 1ml/min and the retention time was about 1.67 minutes for benzapril and 5.0 minutes for amlodipine. The method is selective and able to resolve drug peaks from formulation excipients. The peaks of benzapril and amlodipine were well separated (resolution 11.65). The calibration curves were linear over the concentration range of 80% to 120% (r2 = 0.999 for both the drugs). The proposed method is accurate with 100.72% recovery for benzapril and 99.44% recovery for amlodipine and precise (%RSD of intraday variation were 0.53-0.152 for benzapril and 0.067-1.518 for amlodipine and %RSD of inter day variation were 0.024-1.518 for benzapril and 0.034-1.518 for amlodipine). The method has been used to test market products (six brands) and potency was found within limit (99.02%- 100.02% for benzapril and 97.4%-100.4% for amlodipine). Therefore, this method can be used as a more convenient and efficient option for the analysis of benzapril and amlodipine in tablet dosage form.