Acid-Responsive Polymeric Nanocarriers for Topical Adapalene Delivery

The acne skin is characteristic of a relatively lower pH microenvironment compared to the healthy skin. The aim of this work was to utilize such pH discrepancy as a site-specific trigger for on-demand topical adapalene delivery. The anti-acne agent, adapalene, was encapsulated in acid-responsive polymer (EudragitA (R) EPO) nanocarriers via nanoprecipitation. The nanocarriers were characterized in terms of particle size, surface morphology, drug-carrier interaction, drug release and permeation. Adapalene experienced a rapid release at pH 4.0 in contrast to that at pH 5.0 and 6.0. The permeation study using silicone membrane revealed a significant higher drug flux from the nanocarrier (6.5 +/- 0.6 mu g.cm(-2).h(-1)) in comparison to that (3.9 +/- 0.4 mu g.cm(-2).h(-1)) in the control vehicle (TranscutolA (R)). The in vitro pig skin tape stripping study showed that at 24 h post dose-application the nanocarrier delivered the same amount of drug to the stratum corneum as the positive control vehicle did. The acid-responsive nanocarriers hold promise for efficient adapalene delivery and thus improved acne therapy.