Electrically enhanced transdermal delivery of a macromolecule

The purpose of this study was to establish the delivery parameters for the enhanced transdermal delivery of dextran sulfate (MW 5000 Da). Full-thickness pig skin or epidermis separated from human cadaver skin was used. Silver-silver chloride electrodes were used to deliver the current (0.5 mA cm(-2)). For electroporation experiments, one or more pulses were given using an exponential decay pulse generator. The correct polarity for iontophoresis and pulsing was first established as cathode in the donor. The amount of drug delivered increased with increasing donor concentration up to a point, but not any further. The amount delivered also increased with pulse voltage, the delivery being twice as much as with iontophoresis alone (144.5 +/- 10.35 mug cm(-2)), when 6 pulses of 500 V were applied at time zero before iontophoresis (276 +/- 45.2 mug cm(-2)). It was observed that the amount delivered was a function of increasing pulse length when the apparent charge delivered was kept constant. Transport through pig skin (107.4 +/- 24.4 mug cm(-2)) was found to be comparable with that through human epidermis (84.9 +/- 18.4 mug cm(-2)). in conclusion, we have demonstrated the transdermal delivery of a 5000 Da molecular weight dextran sulfate using iontophoresis. It was also seen that iontophoretic delivery could be enhanced by simultaneous electroporation.