Nanostructured lipid carriers to enhance transdermal delivery and efficacy of diclofenac

Lipid carrier-mediated transdermal drug delivery offers several advantages because it is non-irritating and non-toxic, provides effective control of drug release, and forms an adhesive film that hydrates the outer skin layers. However, to penetrate the deeper skin layers, these formulations need to overcome several barriers in the stratum corneum. This study evaluates factors influencing particle size and drug-loading capacity, which play a key role in drug permeation and efficacy. Diclofenac sodium was chosen as the model drug. The fabrication of diclofenac sodium-loaded lipid nanoparticles was optimized by modulating several parameters, including the lipids and surfactants employed, the drug/lipid ratio, and the pH of the aqueous phase. The physical properties and loading efficiencies of the nanoparticles were characterized. The optimized formulation was then dispersed into a polymer solution to form a gel, which demonstrated a sustained ex vivo permeation of diclofenac sodium over 24 h through excised rat skin and a higher drug penetrating capacity than that of a commercially available gel. In vivo anti-inflammatory activity was assessed in a rat carrageenan-induced paw edema model; the anti-edema effects of the prepared gel and commercially available gel over 24 h were comparable. The present findings indicate the effects of particle size and drug loading on the ability of nanostructured lipid carrier preparations to provide transdermal drug delivery.