Reverse Phase HPLC Method for the Simultaneous Determination of Cetirizine, Verapamil/Diltiazem and Amlodipine

Determination of cetirizine, diltiazem, or verapamil and amlodipine in an active and in dosage formulations has been performed using a simple RP-HPLC method. Rosuvastatin is used in this novel RP-HPLC method as an internal standard to improve the selectivity of the method. At 230 nm, the separation was performed using a mobile phase consisting of methanol, acetonitrile, and water mixture in a ratio of 65:5:30, and pH at 2.8 allowed improved separation and faster times of analysis. ICH guidelines have pursued the validation of the method by assessing accuracy, precision (%RSD>2), and linearity (>0.999). The retention times of diltiazem, verapamil, amlodipine, cetirizine, and rosuvastatin was found to be 2.5, 3.2, 4.1, and 6 minutes, respectively. Method specificity was good as no interference of excipients of the tablets were observed in the analysis. The developed method could be used for routine quality control and in biological samples for the analysis of these drugs.