Which modality uses electrical current to drive medications through the skin?

• A. Phonophoresis
• B. Cryotherapy
• C. Ultrasound
• D. Iontophoresis

Answer: (D)

The concept tested here is delivering medications through the skin using electrical current, which is iontophoresis. Iontophoresis applies a low electrical current with an electrode setup so charged drug molecules are pushed through the skin’s outer barrier into deeper tissues. Because it relies on the electrical field, only charged ions can be effectively driven across the skin, allowing local delivery with controlled dosing and limited systemic exposure. This method is commonly used for anti-inflammatory drugs or local anesthetics in topical form.

Phonophoresis, by contrast, uses ultrasound to temporarily increase skin permeability and enhance diffusion, but there’s no electrical current driving the drug into the tissue. Cryotherapy involves cooling the area for therapeutic effects and does not involve drug transport via electrical means. Ultrasound alone uses acoustic energy for therapeutic effects and can aid diffusion in some contexts, but it does not accomplish drug delivery through the skin via electrical current.

So, the modality that uses electrical current to drive medications through the skin is iontophoresis.