Department of Bioscience and Biotechnology, Faculty of Engineering, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.
Int J Pharm. 2011 Apr 15;408(1-2):76-83. doi: 10.1016/j.ijpharm.2011.01.052. Epub 2011 Feb 1.
An amorphous matrix comprised of sugar molecules are frequently used in the pharmaceutical industry. The compression of the amorphous sugar matrix improves the handling. Herein, the influence of compression on the water sorption of an amorphous sugar matrix was investigated. Amorphous sugar samples were prepared by freeze-drying, using several types of sugars, and compressed at 0-443 MPa. The compressed amorphous sugar samples as well as uncompressed samples were rehumidified at given RHs, and the equilibrium water content and glass transition temperature (T(g)) were then measured. Compression resulted in a decrease in the equilibrium water content of the matrix, the magnitude of which was more significant for smaller sized sugars. Diffusivity of water vapor in the sample was also decreased to one-hundredth by the compression. The T(g) value for a given RH remained unchanged, irrespective of the compression. Accordingly, the decrease in T(g) with increasing water content increased as the result of compression. The structural relaxation of the amorphous sugar matrices were also examined and found to be accelerated to the level of a non-porous amorphous sugar matrix as the result of the compression. The findings indicate that pores contained in freeze-dried sugar samples interfere with the propagation of structural relaxation.
一种由糖分子组成的无定形基质经常被用于制药行业。无定形糖基质的压缩可以改善其处理性能。在此，研究了压缩对无定形糖基质的吸湿性的影响。使用几种类型的糖通过冷冻干燥制备无定形糖样品，并在 0-443 MPa 下进行压缩。将压缩的无定形糖样品以及未压缩的样品在给定的 RH 下重新吸湿，并测量其平衡含水量和玻璃化转变温度（T(g)）。压缩导致基质的平衡含水量降低，对于较小尺寸的糖，这种降低的幅度更为显著。通过压缩，水蒸气在样品中的扩散系数也降低到百分之一。对于给定的 RH，T(g)值保持不变，与压缩无关。因此，由于压缩，T(g)随含水量增加而降低的趋势增加。还对无定形糖基质的结构弛豫进行了研究，发现由于压缩，其弛豫速度加快到非多孔无定形糖基质的水平。研究结果表明，冷冻干燥糖样品中的孔会干扰结构弛豫的传播。
