Skin permeation study of dehydroepiandrosterone (DHEA) compared with its alpha-cyclodextrin complex form

Abstract

Several studies have shown that dehydroepiandrosterone (DHEA) has promising uses in a large range of pathologies including age-related illnesses (osteoporosis, atherosclerosis), immune dysfunctions, and cancer. A long-term oral dosage form would be favorable, but this type of medication has not been developed yet because of the important first-pass effect and low and variable bioavailability. A proposed alternative strategy is the preparation of DHEA for transdermal permeation, allowing direct absorption in the systemic circulation. DHEA has shown good permeation properties through the stratum corneum, however its poor water solubility limits its dosage form concentration and represents the major obstacle to the formulation of a reservoir transdermal system. However, alpha-cyclodextrins have been shown to improve the solubility, the dissolution properties, and the partition coefficient of DHEA. This paper deals with the formulation and evaluation of a transdermal gel containing an alpha-cyclodextrin complex with DHEA. In in vitro permeation tests on porcine skin, the formulation containing the complex improved the permeation flux of DHEA. The study also shows that a gel formulation improved drug permeation with respect to simple water suspension.