Spectroscopic Determination and Computational Characterization of the Charge Transfer Complex of Famotidine with Bromanil

Famotidine (FMD), a histamine H₂-receptor antagonist, is commonly used in the management of gastroesophageal reflux disease and gastric ulcers. Despite several reported analytical approaches for its detection, charge-transfer complex (CTC) formation offers a spectrophotometric alternative that uses readily available materials and reproducible conditions. A spectrophotometric method was developed based on the formation of a CTC between FMD and bromanil (BRL). Validation involved investigating reaction stoichiometry, the influence of time and temperature, intra- and interassay precision and accuracy, and application to tablet dosage forms. Additionally, computational modeling was performed to explore the interaction mechanism. The optimized conditions yielded a stable and reproducible BRL-FMD complex. The method demonstrated linearity with <i>R</i> ² of 0.9999 and % RSD of 0.41%, precision, and accuracy for the quantification of FMD in commercial formulations. Computational analysis, using quantum chemistry, complemented the experimental findings, confirming the charge-transfer interaction and identifying the significant stabilizing factors. This study establishes a reliable and economical spectrophotometric assay for FMD based on CTC formation with BRL. The integrated experimental and computational approach provides mechanistic insight and promotes broader application of CTC-based assays in pharmaceutical analysis.