ICH-compliant Spectrophotometric Analysis of Zonisamide and Naltrexone Hydrochloride In Combined Formulations

Abstract

A validated spectrophotometric technique for the quantification of Zonisamide and Naltrexone hydrochloride in both pure drug and synthetic combination formulations was described. This analytical approach employs the zero crossing technique, offering a straightforward, sensitive, accurate, and reproducible means of analysis. In this procedure, zonisamide exhibited a significant derivative absorbance at 267.2 nm (zero-crossing point for naltrexone hydrochloride). Conversely, Naltrexone hydrochloride was quantified at 238.4 nm (zero-crossing point of zonisamide). The method demonstrated excellent linearity for both compounds within a concentration range of 3–21 μg/ml. The method was validated in accordance with the International Council for Harmonization (ICH) Q2(R2) guidelines, confirming its suitability for routine quality control in bulk drugs, mixtures, and formulations containing these two active ingredients.