著者
北岡 宏章 大屋 和美 伯水 英夫
出版者
The Pharmaceutical Society of Japan
雑誌
Chemical and Pharmaceutical Bulletin (ISSN:00092363)
巻号頁・発行日
vol.43, no.10, pp.1744-1750, 1995-10-15 (Released:2008-03-31)
参考文献数
11
被引用文献数
6 6

Nafagrel hydrochloride exists as both a hemihydrate and monohydrate. Conversion from the hemihydrate to the monohydrate is not reversible, and both hydrates can coexist in stable equilibrium between 23% relative humidity (RH) and 64% RH. In order to clarify the dehydration behavior, the kinetics of the thermal dehydration of the hydrates was studied by means of isothermal gravimetry at atmospheric pressure with a controlled water vapor pressure. This revealed that dehydration did not depend on absolute humidity but on RH. The dehydration of the hemihydrate proceeded by two-dimensional gorwth of the nuclei, A2, but the mechanism of monohydrate dehydration changed from A2 to a two-dimensional phase boundary, R2, with an increase in RH. The dehydration of the monohydrate proceeded by R2, resulting in the production of the hemihydrate at 6.5% RH or above. These kinetic analyses showed that the monohydrate dehydrated faster than the hemihydrate.
著者
北岡 宏章 和田 千佐 諸井 黎明 伯水 英夫
出版者
The Pharmaceutical Society of Japan
雑誌
Chemical and Pharmaceutical Bulletin (ISSN:00092363)
巻号頁・発行日
vol.43, no.4, pp.649-653, 1995-04-15 (Released:2008-03-31)
参考文献数
6
被引用文献数
16 35

Differential scanning calorimetry (DSC) curves of levofloxacin hemihydrate measured under various conditions showed different thermograms. These phenomena were attributed to be the dehydration. Dehydration caused a multiple-phase transition. Dehydration at a higher temperature (above 70°C) gave a sharp endothermic peak on the DSC curve due to the melting of the γ form, and at a lower temperature (below 50°C) gave a sharp endothermic peak due to the melting of the α form.In contrast, the thermal behavior of levofloxacin monohydrate was not affected by dehydration. The difference in the thermal behavior between the hemihydrate and the monohydrate might be attributed to a difference in the interaction between levofloxacin and crystal water. Observations by thermomicroscopy, the changes in powder X-ray diffraction patterns during heating, and single X-ray analysis all supported the above interpretation.