A PHYSICOCHEMICAL STUDY ON THE INTERACTION BETWEEN PAPAVERINE AND NATURAL AND MODIFIED BETA-CYCLODEXTRINS

The interaction of the alkaloid drug papaverine (PAP) with different c yclodextrins (CyDs) was investigated. Freeze-drying method was used to prepare solid complexes that were characterized in the solid state us ing differential scanning calorimetry (DSC) and X-ray diffractometry. Circular dichroism spectroscopy (CD) and H-1-NMR was used in an aqueou s solution to obtain information about the inclusion mode of PAP into the cavity of CyDs. beta-cyclodextrin (beta-CyD) and dimethyl-beta-cyc lodextrin (DM-beta-CyD) are able to include the drug but in all cases the stability constant values are very small, indicating a weak host-g uest interaction. No exact information exists about the interaction of PAP with the internal cavity of hydroxypropyl-beta-cyclodextrin (HP-b eta-CyD). Solubility studies in the presence of all CyDs were performe d using Higuchi and Conners methods at 37 degrees C and pH 7.4. The in fluence of complexation on the diffusion rate of PAP through artificia l membranes was evaluated using dialysis bags. Little influence was ob served in the presence of all macrocycles. (C) 1998 Elsevier Science B .V.