1: Pharm Res. 2007 Jun;24(6):1131-7. Epub 2007 Mar 23.

Monitoring of urea and potassium by reverse iontophoresis in vitro.

Wascotte V, Delgado-Charro MB, Rozet E, Wallemacq P, Hubert P, Guy RH, Préat V.

Université Catholique de Louvain, Unité de Pharmacie Galénique, Avenue Emmanuel
Mounier, Brussels, Belgium.

PURPOSE: Reverse iontophoresis is an alternative to blood sampling for the
monitoring of endogenous molecules. Here, the potential of the technique to
measure urea and potassium levels non-invasively, and to track their
concentrations during hemodialysis, has been examined. MATERIALS AND METHODS: In 
vitro experiments were performed to test (a) a series of subdermal urea and
potassium concentrations typical of the pathophysiologic range, and (b) a
decreasing profile of urea and potassium subdermal concentrations to mimic those 
which are observed during hemodialysis. RESULTS: (a) After 60-120 min of
iontophoresis, linear relationships (p < 0.05) were established between both urea
and potassium fluxes and their respective subdermal concentrations. The
determination coefficients were above 0.9 after 1 h of current passage using
sodium as an internal standard. (b) Reverse iontophoretic fluxes of urea and K(+)
closely paralleled the decay of the respective concentrations in the subdermal
compartment, as would occur during a hemodialysis session. CONCLUSIONS: These in 
vitro experiments demonstrate that urea and potassium can be quantitatively and
proportionately extracted by reverse iontophoresis, even when the subdermal
concentrations of the analytes are varying with time. These results suggest the
non-invasive monitoring of urea and potassium to diagnose renal failure and
during hemodialysis is feasible, and that in vivo measurements are warranted.

PMID: 17380270 [PubMed - indexed for MEDLINE]

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