title: Inclusion complexes of trihexyphenidyl with natural and modified cyclodextrins.
abstract: The solubility of trihexyphenidyl (Thp) was improved by its combination with β-cyclodextrin (β-CD) and modified β-CDs. The solubility of Thp was found to be increased in the presence of β-CD, hydroxypropyl-β-cyclodextrin (HP-β-CD), methyl-β-cyclodextrin (Me-β-CD) and sulfobutylether-β-cyclodextrin (SBE-β-CD). In particular, the solubility of Thp in conjunction with SBE-β-CD was increased by a factor of 11. The formation constant (K c ) for the Thp/SBE-β-CD inclusion complex was determined to be 2300 L/mol based on fluorometry data. The structure of the Thp/SBE-β-CD complex in aqueous solution was examined by (1)H-(1)H rotating frame nuclear Overhauser effect spectroscopy (ROESY) NMR, and the phenyl moiety of the Thp was found to coordinate with the secondary hydroxyl face of the SBE-β-CD. A solid Thp/SBE-β-CD inclusion complex was prepared by freeze-drying.
authors.affiliation: Department of Functional Molecular Chemistry, Kobe Pharmaceutical University, 4-19-1 Motoyamakita-machi, Higashinada-ku, Kobe, 658-8558 Japan.
authors.forename: Hideko
authors.initials: H
authors.lastname: Maeda
authors.affiliation: Department of Functional Molecular Chemistry, Kobe Pharmaceutical University, 4-19-1 Motoyamakita-machi, Higashinada-ku, Kobe, 658-8558 Japan.
authors.forename: Risa
authors.initials: R
authors.lastname: Tanaka
authors.affiliation: Department of Functional Molecular Chemistry, Kobe Pharmaceutical University, 4-19-1 Motoyamakita-machi, Higashinada-ku, Kobe, 658-8558 Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Nakayama
keywords: Inclusion complexes; Solubility; Spectrofluorometry; Sulfobutylether-β-cyclodextrin; Trihexyphenidyl