INTERACTION OF SOME BARBITURIC-ACID DERIVATIVES WITH HYDROXYPROPYL-BETA-CYCLODEXTRIN

The interaction between 39 barbituric acid derivatives and hydroxyprop yl-beta-cyclodextrin (HPbetaCD) was studied by reversed-phase charge-t ransfer thin-layer chromatography. Except for one derivative, each bar biturate formed inclusion complexes with HPbetaCD, the complex always being more hydrophilic than the uncomplexed drug. The intensity of int eraction significantly increased with increasing lipophilicity of the guest molecule proving the preponderant role of hydrophobic interactio ns in inclusion complex formation. The di- and trisubstituted derivati ves probably formed complexes of different stoichiometry. Free-Wilson analysis proved that the intensity of interaction increases with incre asing size of the substituents at least in the studied range.