Hui Ou-Yang, Yi Tao, Zheng Qin, Liu Feng
College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, China.
Yao Xue Xue Bao. 2011 Jun;46(6):707-12.
Amorphous drugs have higher solubility, better oral bioavailability and are easier to be absorbed than their crystalline counterparts. However, the amorphous drugs, with weak stability, are so easy to crystallize that they will lose the original advantages. Polarization microscope, scanning electron microscope, differential scanning calorimetry, X-ray diffractomer and Raman spectroscopy were used to study the microcosmic crystallization mechanisms of amorphous indometacin and the performance of the drug crystals. The results showed that the growth rate of amorphous indometacin crystals at the free surface was markedly faster than that through the bulk, and that the crystal growth rate decreased observably after spraying an ultrathin melting gold (10 nm) at the free surface of the drug. These results indicated that the high growth rates of amorphous drugs crystals at the free surface were the key to their stability and that an ultrathin coating could be applied to enhance the stability of amorphous drugs.
无定形药物比其结晶形式的同类药物具有更高的溶解度、更好的口服生物利用度，并且更容易被吸收。然而，无定形药物稳定性较差，极易结晶，从而失去其原有的优势。采用偏光显微镜、扫描电子显微镜、差示扫描量热法、X射线衍射仪和拉曼光谱法研究了无定形吲哚美辛的微观结晶机制及药物晶体的性能。结果表明，无定形吲哚美辛晶体在自由表面的生长速率明显快于在整体中的生长速率，并且在药物自由表面喷涂超薄熔融金（10纳米）后，晶体生长速率显著降低。这些结果表明，无定形药物晶体在自由表面的高生长速率是其稳定性的关键，并且可以应用超薄涂层来提高无定形药物的稳定性。
