ABSTRACT:
Controlled release of drugs onto the epidermis with assurance that the drug remains primarily localized and does not enter the systemic circulation in significant amounts is an area of research that has only recently been addressed with success. Microsponge delivery system comprised of a polymeric bead having network of pores with an active ingredient held within, was developed to provide controlled release of the active whose final target is skin itself. Macroporous microspheres of styrene (monomer) and divinylbenzene (cross-linker) were prepared by suspension polymerization using sodium polyacrylate and sodium sulphate as dispersion stabilizers and benzoyl peroxide as catalyst. Effect of dispersion stabilizers concentration and speed of rotation on particle size distribution of blank microsponges revealed optimized concentrations of dispersion stabilizers and speed of rotation; sodium polyacrylate: sodium sulphate (0.1:1.5) and 450 respectively to get the particles of size smaller than 30µ m, suitable for topical delivery without grittiness. Average production yield of blank microsponges was 82.63±1.34%. Fluconazole was then loaded in these microsponges by entrapment method. Drug release from microsponges was slowed down with increase in cross-linking density while very little influenced by the particle size. The entire active ingredient was released from the network of pores of the beads into the solvent during wetting test for entrapped microsponges. Drug released from all microspongic gel formulations was best fitted in zero-order kinetic model (correlation coefficient = 0.972).