Development and Validation of a Reversed-Phase HPLC Method for Simultaneous Determination of Doxazosin Mesylate and Finasteride

This document describes the development and validation of a reversed-phase HPLC method for simultaneous determination of doxazosin mesylate and finasteride. The method was optimized using a reversed-phase column with an isocratic mobile phase and a flow rate of 1.0 mL/min. The appropriate wavelength for simultaneous determination was found to be 230 nm. The system suitability was evaluated by replicate injection of the same standard solution of DOX and FIN, and the RSD% of the retention times and peak areas was less than 1% for both drugs. The linearity of the method was tested in the concentration range 24.25-291.0 µg/mL for DOX and 122.5-1470.0 µg/mL for FIN. The method was validated for system suitability, linearity, precision, accuracy, robustness, and specificity. The developed method was used to assay DOX and FIN in the commercial tablets, and the results of the assay were in good agreement with the label amount.