Evaluation of preclinical efficacy of apremilast-loaded liquid crystalline nanoparticulate gel in amelioration of atopic dermatitis

Apremilast is a phosphodiesterase-4 inhibitor currently under investigation for managing atopic dermatitis, but it is associated with poor physicochemical properties, majorly affecting its bioavailability. To improve the topical delivery, we have encapsulated apremilast into the liquid crystalline nanoparticles and evaluated its preclinical efficacy against atopic dermatitis. The liquid crystalline nanoparticles were manufactured by the melt emulsification method followed by probe sonication. The prepared nanoparticles were evaluated for particle size, zeta potential, encapsulation efficiency and in vitro release. Further, the apremilast liquid crystalline nanoparticles were loaded into the gel base by magnetic stirring. The gel formulation was evaluated for viscosity, textural profile, drug content, ex vivo permeation, and retention in mice skin. The preclinical efficacy of optimized gel formulation was assessed in 2,4 - dinitrochlorobenzene induced atopic dermatitis in mice model followed by histopathological examination of skin sections. The apremilast was successfully loaded into the liquid crystalline nanoparticles with an average particle size of 180 +/- 0.45 nm and entrapment efficiency of 89.42 +/- 4.27 %. The optimized nanoparticles were successfully loaded into gel base showing pseudoplastic shear thinning behaviour. In vivo preclinical efficacy of the optimized gel formulation revealed improved skin structure in comparison with negative control group. The histopathological examination of mice skin treated with optimized gel formulation resulted in decreased epidermal hyperplasia and intactness of outer keratinized epidermal layer with the inner layer. The outcomes of the apremilast-loaded liquid crystalline nanoparticulate gel demonstrated anti-atopic dermatitis potential.