International journal of pharmaceutics vol:113 issue:2 pages:215-222
A liquid chromatography method using poly(styrene-divinylbenzene) as the stationary phase was used as the analytical method to investigate the stability of the macrolide antibiotic erythromycin in neutral and alkaline solutions (pH 7.5-11). Decomposition of erythromycin A was monitored up to 20% of degradation. Three degradation products were detected: pseudoerythromycin A enol ether, pseudoerythromycin A hemiketal and a hydrolysis product of erythromycin A, i.e., the product with an opened lactone structure. The decomposition kinetics have been studied as a function of the ionic strength, the concentration of the buffer, the amount of methanol in the solvent and the temperature.