A new, simple and sensitive spectrophotometric method for the determination of valacyclovir and cefotaxime has been developed. The method is based on the condensation of valacyclovir and cefotaxime with 1, 2- napthaquinone-4- sulfonic acid sodium (NQS) in alkaline media to yield orange colored products respectively. Valacyclovir and cefotaxime showed maximum absorbance at 495nm and 475nm with linearity was observed in the concentration range of 20- 120 μg/ml and 20-140 μg/ml respectively. The relative standard deviations of 0.363% for valacyclovir and 0.66% for cefotaxime were obtained. The recoveries of valacyclovir and cefotaxime injections are in the range 96.01±0.52 and 98.12±0.96 respectively. The proposed method is simple, rapid, precise and convenient for the assay of valacyclovir and cefotaxime in commercial injection preparations.
