Degradation kinetics of methylnaltrexone bromide aqueous solution
- Author:
Chang-Rang MU
1
Author Information
1. Pharmaceutical College of Henan University
- Publication Type:Journal Article
- Keywords:
Classic isothermal method;
Degradation kinetics;
Methylnaltrexone bromide;
Stability
- From:
Chinese Pharmaceutical Journal
2012;47(13):1060-1064
- CountryChina
- Language:Chinese
-
Abstract:
OBJECTIVE: To investigate the degradation kinetic characteristics of methylnaltrexone bromide aqueous solution and to study the factors that influence methylnaltrexone bromide degradation, thus to provide necessary data for the pharmaceutical research. METHODS: Classical isothermal method was employed to evaluate the degradation kinetic profile of methylnaltrexone bromide under different temperatures, pH values, illumination and concentrations of Fe3+. The activation energy and shelf life were predicted with Arrhenius equation. RESULTS: The degradation of methylnaltrexone bromide aqueous solution complied with first order kinetics. The aqueous solution was stable in an environment of pH 3.51, the higher the temperature was, the larger the degradation kinetic rate constant was. The shelf-life of the aqueous solution was 145 d at room temperature; and the illumination, as well as the existence of Fe3+ could both facilitate the degradation of methylnaltrexone bromide. CONCLUSION: The degradation of methylnaltrexone bromide follows apparent first-order kinetics, and the degradation kinetic rate is affected by Fe3+ and illumination. Moreover, its degradation remarkably and positively correlates with temperature. pH also has an effect on the degradation rate. The kinetic profile provides basis for the investigation of the degradation mechanism and necessary experimental data for the future pharmaceutical research.
