Development of Spectrophotometric Method for Determination of Famotidine in Tablets via Oxidation-Reduction Reaction

A simple and sensitive spectrophotometric method was developed and validated for the determination of famotidine (FAT) in its pure form and in tablet formulations using an oxidation–reduction reaction. The method involves the oxidation of FAT with excess N-bromosuccinimide (NBS) in an acetic acid medium. Subsequently, the residual NBS reacts with p-anisidine (PAN) under acidic conditions to form a reddish-violet brominated product, whose absorbance is measured at 522 nm. Beer’s law was obeyed over the concentration range of 1–20 mg/L, with a molar absorptivity of 2.193 × 10⁴ L mol⁻¹ cm⁻¹. The limits of detection (LOD) and quantification (LOQ) were 0.034 and 0.114 mg/L, respectively. The method demonstrated high accuracy, with a mean recovery of 99.91%, and good precision, with relative standard deviation (RSD) values below 0.38%. The proposed method was successfully applied to the determination of FAT in pharmaceutical tablets.