Iontophoresis is the transdermal introduction of medications using which modality?

• A. Pulsed electrical stimulation
• B. Magnetic field therapy
• C. Transdermal introduction of medications using a direct current
• D. Heat therapy

Answer: (C)

Iontophoresis delivers medication through the skin by using an electric field. Specifically, it relies on a direct current (galvanic current) applied via electrodes placed on the skin to drive charged drug ions into underlying tissues. The drug resides under an electrode with the same polarity as the drug ion, so the current pushes (repels) the ions into the skin, with delivery controlled by the current level and duration. This distinguishes it from other modalities: pulsed electrical stimulation uses bursts of current for nerve or tissue effects, magnetic field therapy relies on magnetic fields rather than electrical movement of ions, and heat therapy uses warmth rather than electrical transport of medications.