Interaction of cyclomaltononaose (delta-CD) with several drugs

The effects of delta-cyclodextrin (delta-CD; cyclomaltononaose) on solubili ty of 14 drugs that are slightly soluble or insoluble in water were studied and compared with those of conventional cyclodextrins (CDs) such as alpha- cyclodextrin (alpha-CD), beta-cyclodextrin (beta-CD) and gamma-cyclodextrin (gamma-CD). In general, delta-CD had a weak complex-forming ability with t he drugs examined in comparison with beta-CD and gamma-CD. However, in the case of digitoxin, delta-CD enhanced solubility of the guest molecules. To determine the mechanism of inclusion complex formation of delta-CD with dig itoxin, the interaction of both drugs uas investigated by the solubility me thod and spectroscopic methods such as ultraviolet (UV) and H-1-NMR (nuclea r magnetic resonance). The changes in chemical shift (H-1) and hypsochromic shift of UV suggested that digitoxin was partially included in the cavity of delta-CD.