title: Assessment of iontophoretic and passive ungual penetration by laser scanning confocal microscopy.
abstract: OBJECTIVE
  To estimate the in vitro ungual penetration depth of sodium fluorescein and nile blue chloride by laser scanning confocal microscopy.
  
  
  METHODS
  The depth, uniformity and pathways of penetration of both markers into human nail during passive and iontophoretic experiments were investigated. The penetration of sodium fluorescein into the dorsal, ventral and intermediate layers of the nail was also studied. Transversal images were used to estimate directly the relative penetration of the markers with respect to the complete thickness of the nail. "Exposed layer" images allowed estimating the depth of penetration by taking xy-plans, starting by the exposed layer, and following the z axis into the nail.
  
  
  RESULTS
  The fluorescent markers penetrated 7-12% of the nail thickness. Iontophoresis increased penetration of both markers compared to passive diffusion. However, ungual penetration was not modified by the intensity of current applied. Penetration into the dorsal, ventral, and intermediate nail layers was similar. The method developed allowed inter- and intra- nail variability to be accounted for.
  
  
  CONCLUSIONS
  Iontophoresis enhanced moderately the penetration of the two markers into the nail plate as compared to passive diffusion. The confocal images suggested the transcellular pathway to be predominant during both passive and iontophoretic experiments.
authors.affiliation: Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
authors.forename: Julie
authors.initials: J
authors.lastname: Dutet
authors.forename: M Begoña
authors.initials: MB
authors.lastname: Delgado-Charro
mesh_terms: D004058:Diffusion; D019793:Fluorescein / Q000008:administration & dosage* / Q000032:analysis / Q000378:metabolism; D005456:Fluorescent Dyes / Q000008:administration & dosage* / Q000032:analysis / Q000378:metabolism; D006801:Humans; D007478:Iontophoresis; D018613:Microscopy, Confocal; D009262:Nails / Q000378:metabolism* / Q000648:ultrastructure; D010078:Oxazines / Q000008:administration & dosage* / Q000032:analysis / Q000378:metabolism; D010539:Permeability
chemical_list: D005456:Fluorescent Dyes; D010078:Oxazines; C008619:Nile Blue; D019793:Fluorescein