Iontophoresis of a 13 kDa protein monitored by subcutaneous microdialysis in vivo.

The purpose of this study was to optimize parameters pertaining to microdialysis technique so as to make this method feasible for evaluating transdermal transport of macromolecules. Microdialysis experiments were performed in vivo using hairless rats with daniplestim as the model protein. Two perfusion fluids - phosphate-buffered saline (PBS) and 3% dextran in PBS - were evaluated with respect to their effect on sample volume retrieval and recovery of the target protein from the microdialysis probe. Incorporation of dextran-60 in the perfusion fluid reduced fluid loss to 10% as opposed to 34% in the absence of dextran-60. Improvement in daniplestim recovery was also seen with dextran-PBS (56.5 ± 10.3%) as the perfusion fluid than with PBS alone (26.7±4.5%). Subcutaneous levels of daniplestim were measured following iontophoresis after improving recovery and minimizing fluid loss from the microdialysis probe.