高分子量マクロゴール中におけるアスピリン結晶の成長と分解

抄録

The state of aspirin mixed in the solid Macrogol was examined. Macrogol-6000 and 30% (w/w) aspirin were mixed at 70°, 90°, and 110°, and aged at the same temperature. After the mixture cooled, various tests were carried. As the aging time became longer and the temperature higher, the sample became more transparent and had less consistency by both transparency test and thermal analysis. When a high temperature was used or long time spent for aging, X-ray diffraction patterns and infrared (IR) spectra indicated that aspirin in the mixture was in a liquid state at room temperature. The presence of acetylated Macrogol in the mixture was estimated from nuclear magnetic resonance (NMR) and IR spectra, and by a stoichiometric method, and the presence of salicylic acid was confirmed from ultraviolet ( UV) spectra. It is concluded that transesterification between aspirin and Macrogol 6000 decomposed part of aspirin to salicylic acid, and formation of acetylated Macrogol from Macrogol. Lowering of consistency and increased transparency of the mixture may be due to one of the following three reasons : (1) Dissolution of aspirin into Macrogol, of lower molecular weight formed by lowering of molecular weight of Macrogol 6000 due to heating in the presence of aspirin, (2) complicated lowering of the melting point by four ingredients (aspirin, Macrogol, salicylic acid, and acetylated Macrogol), and (3) delay of crystal growth of aspirin in the mixture.