Simultaneous Estimation of Minoxidil and Aminexil in Bulk and Pharmaceutical Formulations by RP-HPLC Method

A new RP-HPLC method was developed for the simultaneous estimation of minoxidil and aminexil in bulk and pharmaceutical formulations. The method used an Agilent C18 column with an isocratic mode of 0.1% orthophosphoric acid and methanol (60:40 v/v) at a 1 ml/min flow rate. It demonstrated linearity in the 50-150 µg/ml range for both compounds, with a correlation coefficient of 0.999. The LOD and LOQ for aminexil were 0.0146 mg/ml and 0.0486 mg/ml, respectively, and for minoxidil, they were 0.046 mg/ml and 0.155 mg/ml. The method showed high accuracy with recovery rates of 99.00% for minoxidil and 100.00% for aminexil, and it was validated for linearity, range, accuracy, precision, specificity, and robustness according to ICH guidelines.