Study of the Interaction of Some Steroidal Drugs with Cyclodextrin Derivatives

Abstract

Spectral mapping (SPM) technique has been employed for the separation of the strength and selectivity of interaction among 13 steroidal drugs and 7 different cyclodextrins (CDs) or CD derivatives. The potency values were considered as the best indicators of the capacity of drugs and CDs to interact with each other. Both drugs and CDs show marked differences in their capacity to form inclusion complexes. Because of the larger diameter of the cavity τ‐CDs showed higher interactive forces than β‐CD derivatives did. Substituents on the CD ring also modified the strength and selectivity of interaction. Stepwise regression analysis proved that the electron withdrawing power of substituents exerted the highest impact on both strength and selectivity of interaction. The data suggest that the interaction between steroidal drugs and CDs depends on the sterical correspondence between the dimensions of the CD cavity and the bulky ring structure of drugs and on the polar interactions between the hydrophilic substituents of drugs pointing outward from the CD cavity and the polar hydroxyl groups in the outer sphere of CD molecules.