Iontophoretic delivery of peptide drugs

The utility of iontophoresis, the electrically assisted delivery of drugs across the skin, to overcome some of the obstacles of peptide delivery has been widely reported in the literature. Iontophoresis offers similar advantages to passive transdermal delivery in that it is non-invasive and can deliver drugs in a continuous fashion over a prolonged period of time. However, unlike passive delivery iontophoresis is capable of delivering larger hydrophilic molecules, such as peptides, in a variety of complex dosing scenarios. Human studies have been performed to demonstrate the safe, effective and reproducible delivery of intact peptides to the systemic circulation. Plasma concentration-time profiles from these studies indicate that steady-state plasma levels are achieved rapidly and the decline in plasma levels appears to be absorption limited rather like an intramuscular bolus injection. However, short lag times are observed which are consistent with diffusion across the outermost layers of the skin but shorter than those typically associated with passive transdermal diffusion. In all reported human clinical trials iontophoretic patches appeared to be well tolerated. Iontophoretic drug delivery offers non-invasive, continuous and pulsatile delivery as well as preprogrammed complex dosing regimes. Small battery powered wearable systems for peptide drugs are currently being developed. The non-invasiveness and wide utility of iontophoresis offer a real benefit in convenient drug delivery for the patient.