Design and optimization of nanoemulsion system by simplex lattice design method to improve solubility of topical diclofenac sodium

Diclofenac sodium is the most widely prescribed NSAIDs, but it has side effects on the GI tract. To overcome this, it can be formed in topical delivery. Diclofenac sodium is included in BCS class II with a log P value of 1.1. Diclofenac sodium can be designed in a nanoemulsion system to increase solubility and penetration effect on the skin. Nanoemulsion is a novel drug delivery consisting of two immiscible liquids, water and oil, which are stabilized by surfactant and cosurfactant. The components ratio of nanoemulsion must be appropriately combined to produce desirable properties, including small particle sizes and stable systems. Determining their optimal ratio is possible via the simplex lattice design (SLD) method. The SLD method was utilized as an optimization technique to generate model formulations of nanoemulsions by the nanoemulsion region extracted from the pseudo-ternary phase diagram. Nanoemulsion was prepared between water, oleic acid (oil), Tween 80-Span 80 (surfactant), and ethanol (cosurfactant) by low energy emulsification method. Their characteristics were evaluated. Tween 80-Span 80 and ethanol with a 2:1 ratio was chosen because they showed maximum nanoemulsion region. The optimal nanoemulsion formulation comprises 15.28% water, 21.25% oil, and 63.47% emulsifier. The results of nanoemulsion characteristics were good, with 108.8 nm particle size, 0.443 PDI, 99.8% transmittance, and 5.276 pH. The observed values were not significantly different from the predicted values. The utilization of the simplex lattice design method in the optimization of nanoemulsions is advantageous for the advancement of pharmaceutical development.