title: Water vapor adsorption behavior of sodium deoxycholate anhydrous forms.
abstract: Pseudopolymorphism of sodium deoxycholate (NaDC) was investigated. Intact NaDC (dihydrate) was dried at 60 degrees C under reduced pressure resulting an anhydrous amorphous phase. On the other hand, intact NaDC was altered to an anhydrous crystalline form by heating at 200 degrees C. The water vapor adsorption and desorption isotherms of dehydrated NaDCs were determined using an automatic gravimetric water vapor adsorption analyzer. In the case of NaDC dehydrated at 60 degrees C, the weight was increased in rising relative humidity and it was transformed into the NaDC tetrahydrate above 60% RH, which was identified by TG/DTA and powder X-ray diffraction. During the water vapor adsorption process of the sample dehydrated at 200 degrees C, the NaDC dihydrate was obtained in the range of 50 to 70% RH and then transformed into the NaDC octahydrate above 85% RH. The NaDC octahydrate was characterized by TG/DTA and powder X-ray diffraction for the first time. During the desorption process, the octahydrate was changed to the tetrahydrate between 80 and 40% RH.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, Japan. onomafOr@daiichipharm.co.jp
authors.forename: Makoto
authors.initials: M
authors.lastname: Ono
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Anzai
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Tozuka
authors.forename: Kunikazu
authors.initials: K
authors.lastname: Moribe
authors.forename: Toshio
authors.initials: T
authors.lastname: Oguchi
authors.forename: Keiji
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D000327:Adsorption; D003840:Deoxycholic Acid / Q000737:chemistry*; D004055:Differential Thermal Analysis; D013696:Temperature; D014835:Volatilization; D014867:Water; D014961:X-Ray Diffraction
chemical_list: D003840:Deoxycholic Acid; D014867:Water