Methoxy poly(ethylene glycol)-block-poly(D,L-lactic acid) copolymer nanoparticles as carriers for transdermal drug delivery

This work evaluates the transdermal drug delivery properties of amphiphilic copolymer self-assembled nanoparticles by skin penetration experiments in vitro. Paclitaxel-loaded methoxy poly(ethylene glycol)-block-poly(D,L-lactic acid) diblock copolymer nanoparticles (PNPs) were prepared by a solid dispersion technique and were applied to the surface of excised full-thickness rat skin in Franz diffusion cells. HPLC, transmission electron microscopy, Fourier transform infrared spectroscopy and H-1 NMR were used to assay the receptor fluid. The results show that the amphiphilic copolymer nanoparticles with the entrapped paclitaxel are able to penetrate rat skin. Ethanol can improve the delivery of PNPs and increase the cumulative amount of paclitaxel in the receptor fluid by 3 times. Fluorescence microscopy measurements indicate that the PNPs can penetrate the skin not only via appendage routes including sweat ducts and hair follicles but also via epidermal routes. (C) 2007 Society of Chemical Industry.