Degradation kinetics of metronidazole in solution

✍ Scribed by Da-Peng Wang; Ming-Kung Yeh

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 433 KB
• Volume: 82
• Category: Article
• ISSN: 0022-3549
• DOI: 10.1002/jps.2600820121

✦ Synopsis

The degradation kinetics of metronidazole in aqueous solutions of pH 3.1 to 9.9 under accelerated storage conditions were studied. The stability of metronidazole in solutions containing propylene glycol or polyethylene glycol 400 was also investigated. The reaction order for metronidazole in these aqueous and solvent systems followed pseudo-first-order degradation kinetics. The degradation rate of metronidazole was invariant under various total buffer concentrations at each specific pH within the investigated pH range. These results indicate that no general acidibase catalysis imposed by acetate, phosphate, and borate buffer species is responsible for the degradation of metronidazole. The catalytic rate constants for hydrogen ion, water, and hydroxyl ion for the degradation of metronidazole were 6.1 1 x M/s, 3.54 x 1 O-' Us, and 4.10 x M/s, respectively. The pH-rate profile shows a pH-independent region of pH 3.9-6.6. Maximum stability of metronida-