iontoforesi

Iontoforesi, also known as iontophoresis, is a noninvasive technique that uses a mild electrical current to drive charged ions through a barrier, most commonly the skin or mucous membranes. The electric field causes electromigration of ions in the formulation, and in many tissues an electroosmotic flow that can aid transport of neutral or larger molecules. Delivery efficiency depends on current density, application time, molecule charge and size, formulation pH, and the barrier properties.

Applications include transdermal drug delivery for local anesthesia (lidocaine), anti-inflammatory agents (diclofenac), hormones, and peptides; research use to study skin permeability; and clinical treatment of hyperhidrosis with daily or periodic tap-water iontophoresis. The method is also employed in dermatology and pharmacology to assess permeability and to enhance localization of therapeutics.

Technique and devices: usually direct current at low current densities, typically 0.1–0.5 mA per cm2, delivered via surface electrodes. Treatment durations range from several minutes to about half an hour, depending on the drug and goal. Formulations should maintain adequate ionization and be compatible with the electrode system to minimize irritation and pH shifts at the skin.

Safety and limitations: potential skin irritation, redness, or burns if the current is too high or applied improperly. Effectiveness varies with skin condition, temperature, and formulation; not all drugs are suitable for iontophoresis. Electrolysis at the electrodes can cause pH changes that irritate tissue.

History: The phenomenon has been studied since the early 20th century, with modern clinical and consumer devices becoming common in the late 20th century.