What type of current does iontophoresis use?

• A. Direct current; polarity doesn't change
• B. Alternating current
• C. Pulsed current
• D. Biphasic current

Answer: (A)

Iontophoresis relies on a steady, unidirectional current to push charged drug molecules through the skin. With a constant polarity, the same-charge drug is repelled from the electrode into the underlying tissues, creating a continuous, directional transport and predictable dosing. If the current were to reverse direction, as with alternating or biphasic or pulsed currents, the net movement of ions would be reduced because the ions would be pulled back during the opposite phase, and surface pH changes from electrolysis could irritate the skin and hinder delivery. Keeping polarity fixed ensures consistent ion migration, which is why direct current is used.