title: Iontophoretic transdermal sampling of iohexol as a non-invasive tool to assess glomerular filtration rate.
abstract: OBJECTIVE
  To explore the potential of non-invasive reverse iontophoresis transdermal extraction of iohexol as a marker of glomerular filtration rate.
  
  
  METHODS
  A series of in vitro experiments were undertaken to establish the feasibility of iohexol reverse iontophoresis and to determine the optimal conditions for the approach. Subsequently, a pilot study in paediatric patients was performed to provide proof-of-concept.
  
  
  RESULTS
  The iontophoretic extraction fluxes of iohexol in vitro were proportional to the marker subdermal concentration and the reverse iontophoretic technique was able to track changes dynamically in simulated pharmacokinetic profiles. Reverse iontophoresis sampling was well tolerated by the four paediatric participants. The deduced values of the iohexol terminal elimination rate constant from transdermal reverse iontophoresis sampling agreed with those estimated by conventional blood sampling.
  
  
  CONCLUSIONS
  Reverse iontophoretic transdermal extraction fluxes mirrored the subdermal concentration profiles of iohexol, a relatively large neutral marker of glomerular filtration both in vitro and in vivo. The efficiency of extraction in vivo was well predicted by the in vitro model used.
authors.affiliation: Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA1 7AY, UK.
authors.forename: Asma
authors.initials: A
authors.lastname: Djabri
authors.forename: William
authors.initials: W
authors.lastname: van't Hoff
authors.forename: Penelope
authors.initials: P
authors.lastname: Brock
authors.forename: Ian C K
authors.initials: IC
authors.lastname: Wong
authors.forename: Richard H
authors.initials: RH
authors.lastname: Guy
authors.forename: M Begoña
authors.initials: MB
authors.lastname: Delgado-Charro
mesh_terms: D000279:Administration, Cutaneous; D000293:Adolescent; D000818:Animals; D002648:Child; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D007472:Iohexol / Q000008:administration & dosage / Q000378:metabolism*; D007478:Iontophoresis / Q000379:methods*; D008297:Male; D009924:Organ Culture Techniques; D010865:Pilot Projects; D012869:Skin Absorption / Q000187:drug effects* / Q000502:physiology*; D013552:Swine
chemical_list: D007472:Iohexol