Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland.
Mol Pharm. 2012 Jun 4;9(6):1748-63. doi: 10.1021/mp300067r. Epub 2012 May 11.
Antibiotics are chemical compounds of extremely important medical role. Their history can be traced back more than one hundred years. Despite the passing time and significant progress made in pharmacy and medicine, treatment of many bacterial infections without antibiotics would be completely impossible. This makes them particularly unique substances and explains the unflagging popularity of antibiotics within the medical community. Herein, using dielectric spectroscopy we have studied the molecular mobility in the supercooled liquid and glassy states of three well-known antibiotic agents: azithromycin, clarithromycin and roxithromycin. Dielectric studies revealed a number of relaxation processes of different molecular origin. Besides the primary α-relaxation, observed above the respective glass transition temperatures of antibiotics, two secondary relaxations in the glassy state were identified. Interestingly, the fragility index as well as activation energies of the secondary processes turned out to be practically the same for all three compounds, indicating probably much the same molecular dynamics. Long-term stability of amorphous antibiotics at room temperature was confirmed by X-ray diffraction technique, and calorimetric studies were performed to evaluate the basic thermodynamic parameters. Finally, we have also checked the experimental solubility advantages given by the amorphous form of the examined antibiotics.
抗生素是具有极其重要医学作用的化学化合物。它们的历史可以追溯到一百多年前。尽管时间流逝，药物学和医学取得了重大进展，如果没有抗生素，许多细菌感染的治疗将完全不可能。这使得它们成为特别独特的物质，并解释了抗生素在医学界中持久不衰的受欢迎程度。在这里，我们使用介电光谱法研究了三种著名抗生素药物：阿奇霉素、克拉霉素和罗红霉素在过冷液体和玻璃态中的分子迁移。介电研究揭示了许多不同分子起源的松弛过程。除了在抗生素各自的玻璃化转变温度以上观察到的主要α松弛外，还在玻璃态中鉴定出了两个次要松弛。有趣的是，对于所有三种化合物，次级过程的脆性指数和活化能实际上是相同的，表明可能具有相同的分子动力学。通过 X 射线衍射技术证实了无定形抗生素在室温下的长期稳定性，并进行了量热研究以评估基本热力学参数。最后，我们还检查了所研究抗生素的无定形形式带来的实验溶解度优势。
