LAUSR

Abstract The aim of this study was to investigate the skin permeability of a hydrophobic drug when using poly( dl -lactide-co-glycolide)-block-poly(ethylene glycol)-block-poly( dl -lactide-co-glycolide) triblock copolymers (PLGA-PEG-PLGA) as a drug carrier. Two types of PLGA-PEG-PLGA nanoparticles with an average particle size of 30 nm and poly( dl -lactide-co-glycolide) (PLGA) nanoparticles for comparison were prepared using a combination of an antisolvent diffusion method with preferential solvation. Cyclosporin A was used as a hydrophobic model drug. From the results of the in vitro release test, it was confirmed that the release of the drug from the nanoparticles was relatively fast in the PLGA-PEG-PLGA nanoparticles. This result suggested that, compared to PLGA nanoparticles, the thermodynamic activity of PLGA-PEG-PLGA nanoparticles increased and the diffusion of the drug into the stratum corneum was promoted. The results of studies on skin permeability using rat skin and a transdermal delivery route showed that PLGA-PEG-PLGA nanoparticles were useful for efficient drug skin permeation and can deliver the drugs deep into the epidermal and dermal layers. Additionally, in the membrane permeability tests using Strat-M®, which imitates human skin, the membrane permeation amount of the drug was significantly increased when PLGA-PEG-PLGA nanoparticles were used compared with when PLGA nanoparticles were used.