Iontophoresis is a technology which facilitates drug ions through skin by the application of a mild electrical current. Both formulations and device design are very important factors for successful product development. Liquid and hydrogel based formulations are most widely used in conventional iontophoresis systems. However, these systems have their limitations for water-unstable drugs (such as hydrolysis reaction) and high potency drugs (such as peptides). A handy iontophoresis patch was designed for this specific application. This new patch is composed of a dried drug-hold membrane and a liquid reservoir to dissolve the drug at the activation by the patient. The separation of drug and dissolution liquid is to protect the unstable drugs from hydrolysis reaction during the storage period; the membrane has a function of permeability enhancement as well as dry-state drugs holder. A potent vasodilator which can improve the microcirculation in peripheral vascular disease, , but also is very chemically unstable, was investigated using this system. Clinically this drug is administered by injection in Japan; however, it is less efficacious because of under dosage in the peripheral target site and it causes a steal phenomenon by itself. Therefore, there is a considerable interest in the development of transdermal delivery system that would allow high drug concentrations to be delivered to the target site directly. The results showed that this new system can considerably improve the drug stability and enhance the drug permeation through the skin. Pharmacological studies showed a potential application of topical iontophoresis on a vasodilator. This study suggests that the newly developed iontophoresis system is suitable for chemically unstable drugs as well as high efficacy drugs.