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] Related Links Non-invasive monitoring of phenytoin by reverse iontophoresis. [Eur J Pharm Sci. 2004] PMID:15265512 Reverse iontophoresis as a noninvasive tool for lithium monitoring and pharmacokinetic profiling. [Pharm Res. 2004] PMID:15290862 Reverse iontophoresis: a non-invasive technique for measuring blood urea level. [Pediatr Nephrol. 2003] PMID:12898373 Transdermal reverse iontophoresis of valproate: a noninvasive method for therapeutic drug monitoring. [Pharm Res. 2003] PMID:14567648 Lithium monitoring by reverse iontophoresis in vivo. [Clin Chem. 2004] PMID:15192031