Iontophoretic transdermal sampling of iohexol as a noninvasive tool to assess glomerular filtration rate

Purpose

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.