title: The time course of dexamethasone delivery using iontophoresis through human skin, measured via microdialysis.
abstract: METHODS
  Controlled laboratory study.
  
  
  OBJECTIVE
  To determine the time course of dexamethasone sodium phosphate (Dex-P) during iontophoresis to underlying tissues using microdialysis.
  
  
  BACKGROUND
  In human participants, real-time information of Dex-P transdermal delivery during iontophoresis is unknown.
  
  
  METHODS
  Sixty-four healthy male participants (mean ± SD age, 24.2 ± 3.3 years; height, 181.8 ± 26.1 cm; mass, 82.4 ± 11.8 kg; subcutaneous fat thickness, 0.61 ± 0.19 cm) were randomly assigned into 1 of 6 groups: (1) 1-mA current, 1-mm probe depth; (2) 1-mA current, 4-mm probe depth; (3) 2-mA current, 1-mm probe depth; (4) 2-mA current, 4-mm probe depth; (5) in vivo retrodialysis; and (6) skin perfusion flowmetry. Microdialysis probes were used to assess the combined recovery (Dex-total) of Dex-P, dexamethasone, and its metabolite.
  
  
  RESULTS
  There was no difference in Dex-total between current intensities (P = .99), but a greater amount of Dex-total was recovered superficially at 1 mm compared to the 4-mm depth (P<.0001). Peak concentration mean ± SD values for the 1- and 2-mA currents at 1 mm were 10.8 ± 8.1 and 7.7 ± 5.5 µg/mL, and at 4 mm were 2.0 ± 0.8 and 1.3 ± 0.9 µg/mL, respectively. Peak skin perfusion was 741.4% ± 408.7% and 711.6% ± 260.8% at baseline for 1- and 2-mA intensities, respectively. Skin perfusion returned to baseline levels earlier during 1-mA intensity at a 110 mA · min dose within the treatment, compared to 2 mA at 60 minutes posttreatment.
  
  
  CONCLUSIONS
  Transdermal delivery of Dex-P during iontophoresis was successfully measured in vivo through human skin. Measurable concentrations of Dex-total were found regardless of current intensity. Although current-induced vasodilation occurred, it did not significantly affect the tissue accumulation of Dex-total.
authors: Department of Health Promotion and Human Performance, Weber State University, Ogden, UT.
authors: Justin H
authors: JH
authors: Rigby
authors: David O
authors: DO
authors: Draper
authors: A Wayne
authors: AW
authors: Johnson
authors: J William
authors: JW
authors: Myrer
authors: Dennis L
authors: DL
authors: Eggett
authors: Gary W
authors: GW
authors: Mack
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D002851:Chromatography, High Pressure Liquid; D003907:Dexamethasone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000032:analysis / Q000493:pharmacokinetics; D005938:Glucocorticoids / Q000008:administration & dosage* / Q000032:analysis / Q000493:pharmacokinetics*; D006801:Humans; D007478:Iontophoresis; D008297:Male; D017551:Microdialysis; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply; D014664:Vasodilation; D055815:Young Adult
chemical_list: D005938:Glucocorticoids; C004180:dexamethasone 21-phosphate; D003907:Dexamethasone
keywords: corticosteroid; skin perfusion; transdermal drug delivery