AN IN-VITRO STUDY OF THE EFFECT OF HYDROCOLLOID PATCH OCCLUSION ON THE PENETRATION OF TRIAMCINOLONE ACETONIDE THROUGH SKIN IN MAN

The aim of this study was to evaluate the effect of occlusion using hy drocolloid-containing patches on in-vitro triamcinolone acetonide (TAC A) penetration of the epidermis while monitoring the uptake of water b y the patches as a result of transepidermal water loss. The hydrocollo id patches were a laminate of a pressure-sensitive hydrophobic adhesiv e (containing a dispersion of 39% of either pectin or carmellose sodiu m) and a polyethylene film. The diffusion of a representative corticos teroid (TACA) through isolated epidermal sheet was shown to depend on the site from which the skin was removed. The two patch-types exhibite d markedly different hydration rates when applied to the membranes. Fo r example, after 96 h the carmellose sodium patch showed ten times the weight increase of the pectin patch. Epidermal diffusion rates were, however, similar, both showing a 3-4-fold enhancement over unoccluded conditions. The increase in TACA diffusion with the patches can be exp lained by the increase in skin hydration that occurs during occlusion. Despite the large differences in transepidermal water transfer throug h the epidermal membranes with the two types of hydrocolloid patch, ho wever, this level of stratum corneum hydration was apparently similar. As the rate of diffusion was also independent of hydrocolloid patch c omponent, it seems possible that the hydrophobic component of the patc h matrix may also influence the level of skin hydration and consequent drug diffusion.