title: Do amorphous troglitazones prepared from two diastereomer-pairs have the same molecular mobility and crystallization rate at the surface?
abstract: The surface of amorphous compounds crystallizes faster compared to the bulk. This suggests that molecules at the surface have high molecular mobility. Crystallization behavior is affected by various factors including molecular weight and glass transition temperature (T(g)). In this study, we focus on troglitazone which is composed of diastereomers, RR/SS and RS/SR, as model compound, because each diastereomer has the same molecular weight and similar chemical structure. Troglitazone is isolated into each diastereomer, and both amorphous prepared from RR/SS and RS/SR showed similar T(g) (around 60°C). The surface relaxation of each amorphous troglitazone prepared from two diastereomers, RR/SS and RS/SR, was determined to compare surface molecular mobility, using inverse gas chromatography under dry conditions. As a result, amorphous prepared from RS/SR, showed the shorter surface relaxation time at 40°C (temperature below T(g)), which means it has higher molecular mobility than that from RR/SS at the surface although both have the same molecular weight and similar T(g). Microscopy analysis was conducted to observe the crstallization behavior at the surface of amorphous troglitazone in conditions of high temperature and humidity. Micrographs showed that crystallization area at the surface of amorphous prepared from RS/SR, which showed the shorter surface relaxation time, increased faster than that of the amorphous prepared from RR/SS. Although the reason for the difference in the surface relaxation time of each amorphous troglitazone could not be determined, factors such as the difference of configuration might affect the difference.
authors: Formulation Technology Research Laboratories, Daiichi Sankyo Co., Ltd., Tokyo, Japan. furuyama.naho.gh@daiichisankyo.co.jp
authors: Naho
authors: N
authors: Furuyama
authors: Susumu
authors: S
authors: Hasegawa
authors: Shuichi
authors: S
authors: Yada
authors: Takeshi
authors: T
authors: Hamaura
authors: Naoki
authors: N
authors: Wakiyama
authors: Etsuo
authors: E
authors: Yonemochi
authors: Katsuhide
authors: K
authors: Terada
authors: Graham
authors: G
authors: Buckton
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry*; D002839:Chromans / Q000737:chemistry*; D002849:Chromatography, Gas; D003460:Crystallization; D013237:Stereoisomerism; D013499:Surface Properties; D045162:Thiazolidinediones / Q000737:chemistry*; D044366:Transition Temperature; D000077288:Troglitazone
chemical_list: D000970:Antineoplastic Agents; D002839:Chromans; D045162:Thiazolidinediones; D000077288:Troglitazone