Validated Stability−Indicating LC Method for Estimation of Amoxicillin Trihydrate in Pharmaceutical Dosage Forms and Time-Dependent Release Formulations

The objective of this study was to establish a validated stability-indicating LC method for routine analysis of amoxicillin trihydrate in bulk drug samples, different pharmaceutical formulations, and degradation kinetics of the drug under different ICH recommended stress conditions. Chromatographic separation was achieved by a Capacel Pak C18 column with 50:50% v/v methanol-0.02 M phosphate buffer as mobile phase having pH 3.5 and flow rate of 1.0 ml/min; with UV absorbance at 229 nm. The method was validated for system suitability, linearity, precision, accuracy, robustness, specificity and sensitivity. The drug was subjected to stress degradation by exposure to acid and alkaline hydrolysis, oxidation, and photodegradation. It was observed that peaks of all degradation products were well resolved from the pure drug with significantly different retention times, which indicated the specificity and stability-indicating properties of the method. When the utility of the method was verified by analysis of the drug in marketed formulations and in-house time-dependent release tablet formulations, the assay was found to be 99.6–100.4%. Statistical analysis proves that the method is repeatable, selective, and accurate for the estimation of amoxicillin trihydrate in bulk drug samples and also in pharmaceutical formulations.