Transdermal delivery of interferon alpha-2B using microporation and iontophoresis in hairless rats

Purpose. To demonstrate transdermal delivery of interferon alpha-2b (IFN alpha 2b) in hairless rats through aqueous microchannels (micropores) created in the skin and enhanced by iontophoresis. Materials and Methods. The Altea Therapeutics PassPort(TM) System was configured to form an array of micropores (2.0 cm(2); 72 micropores/cm(2)) on the rat abdomen. The transdermal patch (Iomed TransQ1-GS-hydrogel) was saturated with an IFNa2b solution (600 mu g/ml) and applied for 4 h. Delivery was evaluated with and without cathodic iontophoresis (0.1 mA/cm(2)). Intravenous delivery (0.4 mu g/100 g body weight) was performed to support pharmacokinetic calculations. Results. IFN alpha 2b was not delivered through intact skin by itself (passive delivery) or during iontophoresis. However, passive delivery through micropores was achieved in vivo in rats. A dose of 397 +/- 67 ng was delivered over 6 h, with steady state serum concentrations reaching a plateau at 1 h post-patch application. These levels dropped rapidly after patch removal, and returned to baseline within 2 h of patch removal. Iontophoresis-enhanced delivery through micropores resulted in a two-fold increase in the dose delivered (722 +/- 169 ng) in the hairless rat. Conclusions. In vivo delivery of IFN alpha 2b was demonstrated through micropores created in the outer layer of the skin. Iontophoresis enhanced delivery through microporated skin in hairless rats.