Mihranyan A, Strømme M, Ek R
Department of Pharmacy, BMC, Uppsala University, Box 580, 75123 Uppsala, Sweden.
Eur J Pharm Sci. 2006 Feb;27(2-3):220-5. doi: 10.1016/j.ejps.2005.10.002. Epub 2005 Nov 28.
The stability of crystalline acetylsalicylic acid (ASA) powder in binary mixtures with cellulose powders was investigated to reveal information about the influence of the cellulose structural properties on the moisture-induced ASA degradation. Different cellulose powder samples were manufactured and characterized by X-ray diffraction and N2 BET gas adsorption. The degradation patterns in ASA/cellulose mixtures were monitored as a function of salicylic acid increase versus time under various relative humidity conditions at 50 degrees C. The crystallinity index of cellulose samples varied between approximately 49 and 95%. The results indicated that cellulose powder with the lowest crystallinity index exhibited lower degradation rates than the samples with the higher crystallinity index. It should be noted that higher ASA degradation rates were observed in the samples with comparably lower moisture contents. This effect was most pronounced in the 1:3 (w/w), ASA/cellulose mixtures, whereas in 3:1 (w/w), ASA/cellulose mixtures the effect was less obvious. The findings emphasise the importance of cellulose structural organisation when governing the moisture's partition between cellulose and ASA during the hydrolytic degradation.
研究了结晶型乙酰水杨酸(ASA)粉末与纤维素粉末二元混合物的稳定性,以揭示纤维素结构性质对水分诱导的ASA降解的影响信息。制备了不同的纤维素粉末样品,并通过X射线衍射和N2 BET气体吸附进行表征。在50℃的各种相对湿度条件下,监测ASA/纤维素混合物中水杨酸增加量随时间变化的降解模式。纤维素样品的结晶度指数在约49%至95%之间变化。结果表明,结晶度指数最低的纤维素粉末的降解速率低于结晶度指数较高的样品。需要注意的是,在水分含量相对较低的样品中观察到较高的ASA降解速率。这种效应在1:3(w/w)的ASA/纤维素混合物中最为明显,而在3:1(w/w)的ASA/纤维素混合物中,这种效应不太明显。这些发现强调了在水解降解过程中,纤维素结构组织在控制纤维素和ASA之间水分分配时的重要性。