Development and Validation of Ratio Spectra Derivative Spectrophotometric Method for Determination of Mefenamic acid and Ethamsylate in combined Formulation

A simple, economical, precise and accurate ratio spectra derivative spectrophotometric method for Mefenamic acid (MEF) and Ethamsylate (ETH) combination has been developed. The method is based on obtaining first derivative of ratio spectra and measuring amplitude at selected wavelength. The derivative amplitudes at 250.99 nm and 287.11 nm were selected for measuring the response of Mefenamic acid (MEF) and Ethamsylate (ETH) respectively. Beer's law is obeyed in the concentration range of 10–30 μg mL⁻¹ for both the drugs. The % assay was found to be in the range 98.0 – 101.0% for MEF and 98.91 – 101.72% for ETH by the proposed method. The method was validated with respect to linearity, precision and accuracy. Recovery was found in the range of 98.72 -100.64% for MEF and 98.45 – 101.21% for ETH.