Ovcharova G D, Nacheva R N
Antibiotiki. 1984 Mar;29(3):166-70.
The degradation kinetics of solid sodium ampicillin, ampicillin trihydrate and anhydrous ampicillin was studied in relation to the disintegration level of the powder before and after its screening by the particle size. It was shown that the effect of the powder disintegration level on the degradation rate constant proceeded by the spherical model and the reaction of the antibiotic degradation proceeded according to the equation of the first order reaction. The degradation rate constants of the total fractions and the fractions with the particle size of 60, 80 and 100 micron at elevated and room temperatures and their half-lives were evaluated. Different mechanisms of degradation of three ampicillin forms were shown on the basis of the dependence of the degradation rate constant on the temperature and the data of thin-layer chromatography. Higher stability levels of ampicillin powder with the particle size of 100 micron and anhydrous ampicillin in comparison with sodium ampicillin and ampicillin trihydrate were observed. This allows recommending anhydrous ampicillin for preparation of oral dosage forms.
研究了固体氨苄西林钠、三水合氨苄西林和无水氨苄西林的降解动力学，涉及粉末在按粒度筛选前后的崩解程度。结果表明，粉末崩解程度对降解速率常数的影响符合球形模型，抗生素降解反应按一级反应方程进行。评估了在高温和室温下总级分以及粒径为60、80和100微米级分的降解速率常数及其半衰期。根据降解速率常数对温度的依赖性以及薄层色谱数据，揭示了三种氨苄西林形式不同的降解机制。观察到粒径为100微米的氨苄西林粉末和无水氨苄西林相比于氨苄西林钠和三水合氨苄西林具有更高的稳定性水平。这使得推荐使用无水氨苄西林来制备口服剂型成为可能。
