title: Enhancement of topical delivery from biodegradable nanoparticles.
abstract: OBJECTIVE
  To determine whether and how encapsulation of lipophilic compounds in polymeric nanoparticles is able to improve topical delivery to the skin.
  
  
  METHODS
  The penetration of octyl methoxycinnamate (OMC; Parsol MCX), a highly lipophilic sunscreen, into and across porcine ear skin in vitro was investigated, subsequent to encapsulation in poly(epsilon-caprolactone) nanoparticles, using tape-stripping. Confocal laser scanning microscopy (CLSM) was used to visualize the distribution of nanoparticles, charged with Nile red (NR), a lipophilic and fluorescent dye.
  
  
  RESULTS
  Quantification of OMC in the skin using tape-stripping demonstrated that nanoparticulate encapsulation produced a 3.4-fold increase in the level of OMC within the stratum corneum (SC), although the use of nanoparticles did not appear to increase skin permeation (it was not possible to detect OMC in the receiver compartment after 6 h). The confocal images showed that the fluorescence profile observed in the skin after application of NR-containing nanoparticles was clearly different from that seen following application of NR dissolved in propylene glycol. Two hours postapplication of NR-containing nanoparticles, fluorescence was perceptible at greater depths (up to 60 microm) within the skin.
  
  
  CONCLUSIONS
  i) Nanoparticulate encapsulation of OMC increased its "availability" with the SC. ii) The altered distribution of NR when delivered via nanoparticles was due, at least in part, to its altered thermodynamic activity (relative to that in propylene glycol) and, as a result, an increase in its partition coefficient into the SC.
authors.affiliation: Centre interuniversitaire de recherche et d'enseignement, Universities of Geneva and Lyon, Archamps, France.
authors.forename: Rocío
authors.initials: R
authors.lastname: Alvarez-Román
authors.forename: Aarti
authors.initials: A
authors.lastname: Naik
authors.forename: Yogeshvar N
authors.initials: YN
authors.lastname: Kalia
authors.forename: Richard H
authors.initials: RH
authors.lastname: Guy
authors.forename: Hatem
authors.initials: H
authors.lastname: Fessi
mesh_terms: D000287:Administration, Topical; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004337:Drug Carriers; D004339:Drug Compounding; D016503:Drug Delivery Systems; D005456:Fluorescent Dyes; D066298:In Vitro Techniques; D018613:Microscopy, Confocal; D008863:Microspheres; D010539:Permeability; D011091:Polyesters; D012869:Skin Absorption; D012995:Solubility; D013552:Swine
chemical_list: D004337:Drug Carriers; D005456:Fluorescent Dyes; D011091:Polyesters; C016240:polycaprolactone