title: Noninvasive measurement of phenylalanine by iontophoretic extraction in patients with phenylketonuria.
abstract: Phenylketonuria is an autosomal recessive disorder characterized by elevated concentrations of phenylalanine. Elevated phenylalanine concentrations can impair intellectual functions and the disease is treated with a lifelong diet and frequent monitoring of plasma phenylalanine concentrations. Previous in vitro studies have demonstrated the feasibility of iontophoretically enhanced transdermal transport of phenylalanine. Here we evaluate the feasibility of transdermal iontophoretic extraction of phenylalanine in vivo. Phenylalanine was iontophoretically extracted from the skin of healthy volunteers and of patients with phenylketonuria for up to 6 h and concentrations were compared with those measured in plasma. The amount of phenylalanine iontophoretically extracted from the skin declined over time, suggesting contribution of phenylalanine from the skin in the initial extraction. Phenylalanine iontophoretically extracted from skin correlated with plasma phenylalanine levels at plasma levels above 300 micromol/L. This correlation supports the feasibility of iontophoretic phenylalanine extraction for monitoring phenylketonuria.
authors.affiliation: Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah, USA. Nicola.Longo@hsc.utah.edu
authors.forename: N
authors.initials: N
authors.lastname: Longo
authors.forename: S K
authors.initials: SK
authors.lastname: Li
authors.forename: G
authors.initials: G
authors.lastname: Yan
authors.forename: R P
authors.initials: RP
authors.lastname: Kochambilli
authors.forename: K
authors.initials: K
authors.lastname: Papangkorn
authors.forename: D
authors.initials: D
authors.lastname: Berglund
authors.forename: A-H
authors.initials: AH
authors.lastname: Ghanem
authors.forename: C L
authors.initials: CL
authors.lastname: Ashurst
authors.forename: S L
authors.initials: SL
authors.lastname: Ernst
authors.forename: M
authors.initials: M
authors.lastname: Pasquali
authors.forename: W I
authors.initials: WI
authors.lastname: Higuchi
mesh_terms: D001692:Biological Transport; D016022:Case-Control Studies; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004867:Equipment Design; D006801:Humans; D007478:Iontophoresis / Q000295:instrumentation* / Q000379:methods*; D013058:Mass Spectrometry / Q000379:methods; D010649:Phenylalanine / Q000097:blood* / Q000378:metabolism*; D010661:Phenylketonurias / Q000097:blood* / Q000175:diagnosis* / Q000378:metabolism*; D015203:Reproducibility of Results; D012867:Skin / Q000378:metabolism
chemical_list: D010649:Phenylalanine