Relationship between in vivo skin blanching and in vitro release rate for betamethasone valerate creams.

Betamethasone valerate creams from two firms were evaluated using the skin blanching procedure. In both studies, the same cream formulation exhibited significantly higher blanching compared to the other product. An in vitro release rate was determined for these betamethasone valerate cream products using a diffusion cell system, with a cellulose acetate membrane and a 60% ethanol:water receptor medium. The release rate (flux) of betamethasone valerate was higher for the higher blanching formulation and was statistically different from the other product. The integrity of the cellulose acetate membrane in 60% ethanol:water mixture was ascertained using hydrocortisone cream product. The in vitro drug release method, using a diffusion cell system and a synthetic membrane, can serve as a good quality control test method for topical creams.