INTERACTION OF SOME ANTIBIOTICS WITH HYDROXYPROPYL-BETA-CYCLODEXTRIN

The interaction between 19 antibiotics and hydroxypropyl-beta-cyclodex trin (HPbetaCD) was studied by reversed-phase thin-layer chromatograph y. HPbetaCD formed inclusion complexes with 16 compounds, the complex always being more hydrophilic than the uncomplexed drug. The intensity of interaction significantly increased with increasing specific hydro phobic surface area of the guest molecule proving the preponderant rol e of hydrophobic interactions in inclusion complex formation. The inte nsity of the HPbetaCD-drug interaction significantly decreased with in creasing concentration of methanol in the environment indicating that methanol can also enter the cyclodextrin cavity and inhibits competiti vely the inclusion complex formation or the free energy of transfer fr om water to the HPbetaCD cavity should be less negative at higher conc entration of methanol in the aqueous medium.