Spectrophotometric Determination of Cefadroxil and Metyrosine in Dosage Forms

A simple and sensitive spectrophotometric method is described for the determination of cefadroxil and metyrosine in pure form and in pharmaceutical formulations. The method is based on reacting these drugs with 4-aminoantipyrine (AAP) in the presence of an alkaline oxidising agent. The coloured products were measured spectrophotometrically at 500 nm and 470 nm for cefadroxil and metyrosine, respectively. Beer's law was obeyed over the concentration range 1-28 and 2-44 μg ml-1 for cefadroxil monohydrate and metyrosine, respectively. The molar ratio in both cases was established and a proposal for the reaction pathway was suggested. The percentage recoveries obtained were in accordance with those given by the reference methods.