Development and Evaluation of TBF Polymeric Microsponges for Topical Drug Delivery

The objective of the present study was to develop and evaluate sustained delivery of terbinafine hydrochloride from topical polymeric microsponges. Microsponges of ethyl cellulose containing terbinafine hydrochloride were prepared by quasi emulsion solvent diffusion method. Effect of drug polymer ratio on active drug content, particle size and entrapment efficiency were studied. Drug polymer ratio greatly affects properties (entrapment efficiency, active drug content, particle size) of microsponges. Terbinafine hydrochloride microsponges showed highest actual drug content, entrapment efficiency and smaller particle size, so 1.5:1 ratio of drug and polymer was selected for optimization study. Optimization study was carried out by taking internal phase volume, stirring rate, emulsifier concentration as independent variables and their effects on entrapment efficiency, particle size were studied. It was found that as stirring speed increases, the particle size decreases and entrapment efficiency increases, while as volume of dichloromethane increases, particle size decreases. Morphology of obtained microsponges was revealed by scanning electron microscope and was found to be porous and spherical. Optimized formulation of microsponge was dispersed in carbopol gel and evaluated for drug content, pH, viscosity and in vitro drug release. Release of drug was found to be sustained through microsponge gel as compared to marketed product and pure drug gel. Ex vivo drug deposition study was carried using rat abdominal skin. Drug deposition was found to be satisfactory. Prepared polymeric microsponges could be a potential topical drug delivery system in antifungal therapy.