A Validated Stability Indicating RP-HPLC Method for Simultaneous Estimation of Clinidipine and Valsartan in Bulk and Combined Tablet Dosage Forms

The simple, accurate and precise, isocratic RP-HPLC method has been developed and validated for simultaneous estimation of Clinidipine and Valsartan in bulk and tablets dosage forms. The chromatographic separation was achieved on an Waters symmetry C₁₈ (150x4.6 Id, 3.5μ) with a composition of Acetonitrile : phosphate buffer pH 3.5 adjusted with orthophosphoric acid (70:30, v/v) as mobile phase; at a flow rate of 1.0 ml/min. PDA detection of separtion was performed at 254 nm. The retention times were 2.33 and 3.55 minutes. for Clinidipine and Valsartan respectively. Calibration curves were linear (r²>0.998) over the concentration range 1.2-6.0 μg/ml for Clinidipine and 10-50μg/ml Valsartan. The method was validated for accuracy, precision, specificity, linearity, and sensitivity. The proposed method was successfully used for quantitative analysis of tablets. No interference from any component of pharmaceutical dosage form was observed. Validation studies revealed that method is specific, rapid, reliable, and reproducible. The high recovery and low relative standard deviation confirm the suitability of the method for routine determination of Clinidipine and Valsartan in bulk drug and tablet dosage form.