Study on the determination of pharmaceutical products containing amoxicillin and clavulanic acid by HPLC/DAD method

Amoxicillin, a β-lactam antibiotic, is commonly combined with clavulanic acid to extend its antibacterial spectrum. Dissolution testing of pharmaceutical formulations containing these two substances has seldom been reported, largely due to the chemical instability of clavulanic acid and the analytical challenges of simultaneously quantifying both components. This lack of standardized methodology represents a significant research gap in the quality control of Amoxicillin/Clavulanate products. The objective of this study was to develop and validate a robust HPLC/DAD method for dissolution testing of the commercial formulation Vigentin. Dissolution was performed in ultrapure RO water (resistivity 18.2 MΩ·cm at 25 °C) under tightly controlled temperature and stirring speed. Chromatographic analysis employed a C18 column, a sodium dihydrogen phosphate/methanol (95:5, v/v) mobile phase, and UV detection at 220 nm. The validated procedure met all requirements for specificity, repeatability, and system suitability, with excellent linearity (R² > 0.9998). Dissolution quantification of six samples showed amoxicillin release between 93.9% and 98.9%, and potassium clavulanate between 103% and 107%, all above the minimum acceptance criterion of 75%. These results demonstrate that the proposed method effectively fills the methodological gap and provides a feasible, reliable tool for routine pharmaceutical quality evaluation of this clinically important drug combination.