Abstract
Manuscript received: December 2014
The purpose of this study was to evaluate the in vitro release kinetics of Na3CaDTPA, a well-known and widely-used decorporation agent, from a topical microemulsion-gel formulation in comparison with a conventional gel. For the preparation of hydrogels, Carbopol 934 polymer was used. Release studies were conducted using both hydrophobic (polycarbonate) and hydrophilic (mixed cellulose esters) membranes. The release kinetics were evaluated using Franz diffusion cells. The receptor compartment was filled with phosphate buffer pH 7.4 and magnetically stirred at 600 rpm during the experiments. The temperature of the entire setup was maintained at 32 ± 0.5°C. The microemulsion-gel showed a higher diffusion coefficient and a smaller lag time compared to the conventional gel. The release profiles were evaluated using different kinetic models: zero-order, first-order, Higuchi and Korsmeyer-Peppas. Mathematical modelling of the drug release data suggested a quasi-Fickian diffusion mechanism for both conventional and microemulsion-based hydrogels.