Abstract:
The aim of this study was to compare release of a model corticosteroid, triamcinolone acetonide (TA), from hydroalcoholic gels using two commercially available systems. The first system was a standard vertical diffusion cell; the other was a USP dissolution apparatus modified by addition of a recently introduced accessory, the dissolution cell (Enhancer cell, VanKel Industries). Gels containing three drug concentrations, 0.025, 01 and 0.5%,were prepared. The receptor contained ethanol and water in the same proportions as the gel to avoid diffusion of solvent. Release was rapid and linear with the square root of time in all cases. Comparable results with minor differences were obtained with both types of apparatus. The slopes of the release plots obey the Highuchi equation whereby the diffusion coefficient is not concentration-dependent. The modified cells were also used to study the effect of membrane thickness on the release of TA from the 0.1% gel. It was found that the release rate decreased with an increase in membrane thickness suggesting a shift from vehicle-controlled release.