New Spectrophotometric Determination of Tinofovir in Bulk and Pharmaceutical Dosage Form

Two new, selective and sensitive visible spectrophotometric methods (method A and B) have been developed for the estimation of tinofovir in bulk and in pharmaceutical preparations. Tinofovir was subjected to acid hydrolysis and this acid hydrolyzed drug was used for the estimation. Method A is based on the reaction with 3-methyl-2-benzothiazolinone hydrazone in the presence of ferric chloride, to form a colored species with a λmax at 628.5 nm. Method B is based on the reaction with Folin-ciocalteu phenol’s reagent under alkaline condition with a λmax at 768 nm. Beer’s law is obeyed in the concentration range of 5-40 µg/mL for method A and 2-30 µg/mL for method B, respectively. The methods were extended to pharmaceutical formulations and there was no interference from any common pharmaceutical excepients and diluents. The result of analysis has been validated statistically and by recovery studies.