DEVELOPMENT AND VALIDATION OF RP-HPLC METHOD FOR THE SIMULTANEOUS ESTIMATION OF CHLORTHALIDONE AND CILNIDIPINE IN BULK AND COMBINED TABLET DOSAGE FORM

A simple, sensitive, linear, precise and accurate method by Gradient RP-HPLC for the simultaneous estimation of Chlorthalidone and Cilnidipine in bulk and in their combined Tablet Dosage form was developed and validated. The separation of the two drugs was based on Inertsil ODS 3V (250 x 4.6 mm, i. d., 5 mu m) column in a Gradient mode. The mobile phase consisting of 0.025 M Potassium dihydrogen orthophosphate buffer whose pH was adjusted to 2.5 using dilute orthophosphoric acid (solvent A) and Acetonitrile (solvent B), set with gradient programming for 15 min at a flow rate of 1ml/min and the detection of the drugs at 240 nm using a variable PDA detector. The retention times of Chlorthalidone and Cilnidipine were found to be 3.872 minutes and 7.668 minutes respectively. The assay of CHL and CIL in bulk drug and in combined tablet dosage form was found to be 99.72% and 99.90% respectively. Calibration curves were linear for CHL and CIL at concentration ranges of range of 200-600 mu g/ml and 160-480 mu g/ml with the regression coefficient of 0.999 for both the drugs and precise with (% RSD < 2). The LOD was found to be 0.50 mu g/ml and 0.40 mu g/ml for CHL and CIL and LOQ was 1.50 mu g/ml 1.20 mu g/ml for CHL and CIL respectively. The developed method was validated by determining its linearity, accuracy, precision, system suitability and can be employed for routine quality control analysis as per ICH guidelines.