Yip Y W, Po L W
J Pharm Pharmacol. 1979 Jun;31(6):400-2. doi: 10.1111/j.2042-7158.1979.tb13532.x.
The stability of betamethasone-17-valerate in semi-solid bases has been investigated. Emphasis has been placed on the stability problems which could arise upon dilution of proprietary preparations by the use of model systems. Betamethasone-17-valerate has been shown to decompose to betamethasone-21-valerate and betamethasone alcohol. Quantitation of the decomposition was by direct densitometry on thin layer chromatographic plates. The decomposition was found to be an apparent first order process and to depend on the diluent used and its concentration. Attempts were also made to relate the rate of decomposition to the pH of the base used, and to stabilize the products.
已对倍他米松-17-戊酸酯在半固体制剂基质中的稳定性进行了研究。重点关注了使用模型系统稀释市售制剂时可能出现的稳定性问题。已证明倍他米松-17-戊酸酯会分解为倍他米松-21-戊酸酯和倍他米松醇。通过薄层色谱板上的直接光密度测定法定量分解情况。发现分解是一个表观一级过程，且取决于所用稀释剂及其浓度。还尝试将分解速率与所用基质的pH值相关联，并使产品稳定化。
