Potential novel methods for insulin administration: I. Iontophoresis.

It is theoretically feasible to administer an ionized solute transcutaneously using an electric current. Attempts by our group to administer conventional, regular (soluble) insulin to human volunteers by iontophoretic methods failed, probably because such insulin is only weakly ionized and much of it is present in the polymeric form. Animal experiments with pigs defined patterns of portal and systemic insulin concentrations for native insulin secretion, intraperitoneal injection of insulin, and peripheral (intramuscular) injection of insulin. Using a more strongly ionized and predominantly monomeric form of insulin, transcutaneous administration of this hormone by iontophoresis was demonstrated in an experimental animal.