Objective: The purpose of this study was to developed microemulsion based gel formulation for topical delivery of dapsone with an objective to increase the solubility and skin permeability of the drug for treatment of acne. Methodology: The solubility of dapsone in oils, surfactants and cosurfactants was evaluated by saturation solubility to screen the components of the microemulsion. The pseudoternary phase diagrams were constructed using capryol 90 and N-methyl-2 pyrrolidone as the oil phase, Kolliphor EL as surfactant and PEG 400 as the co-surfactant. The system were assessed for drug-loading efficiency and characterized for pH, conductance, viscosity, particle size, drug content, globule size, zeta potential and drug release. Optimized formulation systems were formulated into gel form by using poloxamer- 407 and evaluated for viscosity, spreadability, drug content, stability, in-vitro skin permeation, steady state flux, permeability coefficient, enhancement ration and skin irritation study. Result and Discussion: Globule size of optimized microemulsion (F2) was found to be 27.53 nm, zeta potential was found to be-14.6 mV, permeability of drug from microemulsion within 8h was observed 82%, In- vitro diffusion study showed increase in flux of microemulsion based gel (392.43 μg cm-2 h-1) to that of simple dapsone gel (274.4 ± 0.78 μg cm-2h-1). Draize test revealed absence of irritation and inflammation on rat skin. Conclusion: Microemulsion based gel of dapsone formulation provided better application property and stability in comparison to simple gel.
Key words: Acne vulgaris, Dapsone, Flux, In-vitro skin permeation, Topical delivery.