Cationic Polymeric Nanocapsules as a Strategy to Target Dexamethasone to Viable Epidermis: Skin Penetration and Permeation Studies

The present work aimed to evaluate the behavior of dexamethasone-loaded cationic polymeric nanocapsules in hydrogels, regarding their in vitro drug release and skin drug retention and permeation. Cationic polymeric nanocapsules prepared with Eudragit (R) RS 100 as the polymeric wall had mean particle size of 139 +/- 3.6 nm, positive zeta potential (+11.38 +/- 1.7 mV), and high encapsulation efficiency (81 +/- 2%). After preparation, they were formulated as hydrogels, which showed non-Newtonian, plastic behavior, and acidic pH. Photon correlation spectroscopy analysis of these hydrogels demonstrated the presence of particles with mean particle size close to that of the original colloidal suspensions. The presence of dexamethasone-loaded nanocapsules in hydrogels promoted controlled drug release and an increase in the amount of drug delivered into viable epidermis, the main target tissue to topical glucocorticoid action. Moreover, the formulation did not increase the risk of drug penetration to dermis and permeation to the receptor compartment.