Abstract
The degradation kinetics of sodium sulbactam in various buffer solutions have been investigated over a pH range of 0.74 to 9.95 at 35°C and at an ionic strength of 0.5. The amounts of intact sodium sulbactam and a degradation product were determined by an ion-pair reversed-phase high-performance liquid chromatographic method. The degradation kinetics were consistent with a scheme in which sodium sulbactam is degraded to 2-amino-3-methyl-3-sulfinobutanoic acid and formylacetic acid via 5-carboxy-6-methyl-6-sulfino-4-aza-2-heptenoic acid, which is a labile intermediate. The observed degradation rates at various pHs followed pseudo-first-order kinetics. The pH-rate profile showed that the maximum stability of sodium sulbactam occurred in the pH range of 3.0 to 7.0, and that sodium sulbactam is much more stable than potassium clavulanate over the whole range of pH examined.
