Effects of .BETA.- and .GAMMA.-cyclodextrins on release of betamethasone from ointment bases.

Abstract

In vitro release of betamethasone (BeM) from ointment bases containing BeM or its .beta.- and .gamma.-cyclodextrin (.beta.- and .gamma.-CyD) complexes was investigated by using an ointment release stimulator with artificial double-layer membranes. The release of BeM from gel and hydrophilic ointments was significantly improved by CyD complexation, owing to increases in the apparent rates of dissolution and membrane permeation of the drug. The enhanced release of BeM from the 2 ointments may be attributed to the faster dissolution of the complex and the lower binding affinity of the complex to the ointment bases. An improvement of topical bioavailability of BeM can apparently be obtained by means of inclusion complexation.