Tyrosine-derived nanospheres for enhanced topical skin penetration

  • Int J Pharm. 2008 Feb 28;350(1-2):312-9. doi: 10.1016/j.ijpharm.2007.08.022.
L Sheihet  1 ,  P Chandra ,  P Batheja ,  D Devore ,  J Kohn ,  B Michniak
Affiliations
  • 1. New Jersey Center for Biomaterials, Rutgers - The State University of New Jersey, Piscataway, NJ 08854, USA.
PMID: 17897801 DOI: 10.1016/j.ijpharm.2007.08.022
Abstract

The objective of this study was to investigate the passive skin penetration of lipophilic model agents encapsulated within tyrosine-derived nanospheres. The nanospheres were formed by the self-assembly of a biodegradable, non-cytotoxic ABA triblock copolymer. The A-blocks were poly(ethylene glycol) and the hydrophobic B-blocks were oligomers of suberic acid and desaminotyrosyl-tyrosine alkyl esters. These nanospheres had an average hydrodynamic diameter of about 50nm and formed strong complexes with fluorescent dyes, 5-dodecanoylaminofluorescein (DAF, LogD=7.54) and Nile Red (NR, LogD=3.10). These dyes have been used here as models for lipophilic drugs. The distribution of topically applied nanosphere-dye formulations was studied in human cadaver skin using cryosectioning and fluorescence microscopy. Permeation analysis (quantified fluorescence) over a 24h period revealed that the nanospheres delivered nine times more NR to the lower dermis than a control formulation using propylene glycol. For DAF, the nanosphere formulation was 2.5 times more effective than the propylene glycol based control formulation. We conclude that tyrosine-derived nanospheres facilitate the transport of lipophilic substances to deeper layers of the skin, and hence may be useful in topical delivery applications.

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