title: Evaluation of drug supersaturation by thermodynamic and kinetic approaches for the prediction of oral absorbability in amorphous pharmaceuticals.
abstract: Supersaturation behavior of model drugs, danazol, griseofulvin, itraconazole, vemurafenib, and ER-34122, was analyzed by both thermodynamic and kinetic approaches to better understand the absorption characteristics of amorphous pharmaceuticals. For each amorphous drug, the extent of supersaturation during in vitro dissolution was proved to be similar to that in vivo, which was estimated from relative bioavailability data. The theoretical limit of supersaturation was thermodynamically calculated from several thermal properties and water sorption isotherms of amorphous solids. in vitro and in vivo supersaturation of amorphous vemurafenib was thermodynamically controlled and was in good agreement with the theoretical limit. On the contrary, the supersaturation ratio of the other four drugs was highly overestimated by the thermodynamic calculation. However, it was satisfactorily explained by considering supersaturation stability, which indicated how long supersaturation can be maintained without crystal nucleation. Supersaturation stability was evaluated by measuring the induction time for crystal nucleation kinetically. Concomitant use of thermodynamic and kinetic approaches is, therefore, invaluable in evaluating supersaturation behavior of amorphous materials and assessing development potential of poorly water-soluble drugs.
authors.affiliation: Physical Chemistry, Analytical Research Laboratories, Eisai Product Creation Systems, Eisai Company Ltd., Tsukuba, Ibaraki 300-2635, Japan. s3-ozaki@hhc.eisai.co.jp
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Ozaki
authors.forename: Ikuo
authors.initials: I
authors.lastname: Kushida
authors.forename: Taro
authors.initials: T
authors.lastname: Yamashita
authors.forename: Takashi
authors.initials: T
authors.lastname: Hasebe
authors.forename: Osamu
authors.initials: O
authors.lastname: Shirai
authors.forename: Kenji
authors.initials: K
authors.lastname: Kano
mesh_terms: D000042:Absorption; D000284:Administration, Oral; D007700:Kinetics; D010599:Pharmacokinetics; D013816:Thermodynamics