Which therapy uses electrical current to drive a medication through the skin?

• A. Ultrasound
• B. Iontophoresis
• C. Phonophoresis
• D. Electrical stimulation

Answer: (B)

Iontophoresis uses direct electrical current to move charged medication ions through the skin. The drug must be ionized, and when current is applied, like charges are repelled from the electrode of the same charge and ions migrate into the underlying tissues toward the opposite electrode. The amount delivered depends on current density, duration, electrode size, and the drug’s charge and mobility, providing localized dosing with relatively low systemic exposure. This stands in contrast to phonophoresis, which relies on ultrasound to transiently increase skin permeability without using electrical current to drive the drug. Electrical stimulation, by itself, is used to activate nerves or muscles and is not a method for delivering medications through the skin.