Formulation, Optimization and in vitro Evaluation of Apremilast Nanoemulgel for Topical Delivery

Background: Psoriasis is an autoimmune-mediated disease characterized marked by thickened plaques and erythematous skin, which can be treated by topical delivery of apremilast. The objective of this study was to prepare hydrogel-based nanoemulsions of apremilast for psoriasis therapy with a view of improving its solubility and permeability. Methods: Nanoemulsion components were chosen based on their solubility. Spontaneous emulsification technique was used to formulate apremilast loaded nanoemulsions D-optimal design was used to optimize the formulations. The optimized formulation was assessed for globule size, Polydispersity Index, percentage transmittance, entrapment efficiency, pH, and Transmission Electron Microscopy The optimized nanoemulsion was converted into gels using carbopol 940 and evaluated for critical parameters like spreadability, viscosity and extrudability. In vitro drug release and ex vivo permeation studies were conducted to understand the release kinetics and extent of permeation. Results: Particle size of the nanoemulsions were found to be in the range of 141 nm- 245nm. Transmission electron microscopic images of the optimised formulation showed spherical particles in the nano range. Optimised formulation exhibited excellent entrapment efficiency of 86% and was found to be thermodynamically stable. In vitro drug release studies of the nanoemulgel using the Franz diffusion cell apparatus appeared to follow zero-order kinetics. Ex vivo permeation through porcine skin showed substantial improvement in flux, permeability coefficient, and drug deposition in the skin in the case of nanoemulgel compared to drug dispersion. Conclusion: The results obtained from the studies demonstrated the immense potential of the developed formulations for topical application in psoriasis.