IN-VITRO RELEASE STUDY OF TRETINOIN FROM TRETINOIN CYCLODEXTRIN DERIVATIVE COMPLEXES/

The effects of beta-cyclodextrin, hydroxypropyl beta-cyclodextrin and dimethyl P-cyclodextrin complexes on the in vitro release of tretinoin gels were investigated. The experiments were carried out in a Franz c ell using a silicone membrane as a barrier for the diffusion of the ve hicle. Two types of vehicle were compared: a hydroalcoholic gel in whi ch both tretinoin and the inclusion complexes are soluble, and an aque ous gel in which only the complexes are soluble but tretinoin is dispe rsed. As expected, the release rate of free tretinoin in the hydroalco holic gel is much faster than in the aqueous gel. However,with the aqu eous gel, the cyclodextrin complexation enhances the diffusion rate of the active drug through the membrane, especially with the hydroxyprop yl cyclodextrin inclusion compound. The release of tretinoin is relate d not only to the stability constant of the inclusion, but also to the binding properties of the inclusion compounds to the vehicle.