Formulation and ex vivo evaluation of polymeric nanoparticles for controlled delivery of corticosteroids to the skin and the corneal epithelium

Controlled delivery of corticosteroids using nanoparticles to the skin and corneal epithelium may reduce their side effects and maximize treatment effectiveness. Dexamethasone-loaded ethyl cellulose, Eudragit (R) RS and ethyl cellulose/Eudragit RS nanoparticles were prepared by the solvent evaporation method. Dexamethasone release from the polymeric nanoparticles was investigated in vitro using Franz diffusion cells. Drug penetration was also assessed ex vivo using excised human skin. Nanoparticle toxicity was determined by MIT and H2DCFDA assays. Eudragit RS nanoparticles were smaller and positively charged but had a lower dexamethasone loading capacity (0.3-0.7%) than ethyl cellulose nanoparticles (1.4-2.2%). By blending the two polymers (1:1), small (105 nm), positively charged (+37 mv) nanoparticles with sufficient dexamethasone loading (1.3%) were obtained. Dexamethasone release and penetration significantly decreased with decreasing drug to polymer ratio and increased when Eudragit RS was blended with ethyl cellulose. Ex vivo, drug release and penetration from the nanoparticles was slower than a conventional cream. The nanoparticles bear no toxicity potentials except ethyl cellulose nanoparticles had ROS generation potential at high concentration. In conclusion, the nanoparticles showed great potential to control the release and penetration of corticosteroids on the skin and mucus membrane and maximize treatment effectiveness. (C) 2017 Published by Elsevier B.V.