Formulation, optimization, and in vitro evaluation of nanostructured lipid carriers for topical delivery of Apremilast

This work was aimed to formulate topical Apremilast (APM)-loaded nanostructured lipid carriers (NLCs) for the management of psoriasis. NLCs were prepared by a cold homogenization technique using Compritol 888ATO, oleic acid, Tween 80 and Span 20, and Transcutol P as a solid lipid, liquid lipid, surfactant mixture, and penetration enhancer, respectively. Carbopol 940 was used to convert NLC dispersion into NLC-based hydrogel to improve its viscosity for topical administration. The optimized formulation was characterized for size, polydispersity index (PDI), zeta potential (ZP), percentage of entrapment efficiency (%EE), and surface morphology. Furthermore, viscosity, spreadability, stability, in vitro drug diffusion, ex vivo skin permeation, and skin deposition studies were carried out. APM-loaded NLCs showed a narrow PDI (0.339) with a particle size of 758 nm, a %EE of 85.5%, and a ZP of -33.3 mV. Scanning electron microscopy confirmed spherical shape of NLCs. in vitro drug diffusion and ex vivo skin permeation results showed low drug diffusion, sustained drug release, and 60.1% skin deposition. The present study confirms the potential of the nanostructured lipid form of poorly water-soluble drugs for topical application and increased drug deposition in the skin.