Formulation and Optimization of Topical Solid Lipid Nanoparticles based Gel of Dapsone Using Design of Experiment

The present research work was designed to formulate and evaluate solid lipid nanoparticles (SLN) loaded gel of Dapsone (DS). An attempt was made to develop topical gel with better skin permeation rate.

The SLN formulations of DS were prepared by microemulsion technique and evaluated for its in vitro characteristics. The effect of DS concentration in lipid phase (X1), Gelucire:Precirol ratio (X2) and lipid:Smix ratio (X3) on entrapment efficiency (Y1) and drug release (Y2) from SLN was studied using Box-Behnken design. The result of dependent variables was used to generate polynomial equations and the surface response and counterplots. The optimized SLN formulation was incorporated into the gel using 1% carbopol-934 as a gelling agent. The SLN loaded gel was characterized for pH, viscosity, percent drug content, in vitro drug release and ex vivo permeation through rat skin.

The optimized DS SLN formulation, with 20% drug loading, 0.5:1 as Gelucire : Precirol ratio in lipid phase and 1:3 as Lipid : Smix ratio, showed 95.64±0.2% drug entrapment, 61.1±0.6% of drug release after 8 h, particle size of 168.5 nm with polydispersity index of 0.335 and zeta potential of -16.8±6.1 mV. DS SLN gel demonstrated biphasic release pattern with greater drug permeation through rat skin (Jss, 39.27±2.1 µg/cm2/hr) as compared to plain DS gel (Jss, 22.64±1.8 µg/cm2/hr).

The present study demonstrated DS SLN gel as a possible alternative to a conventional topical formulation for the treatment of acne.