Phonophoresis is best described as:

• A. Phonophoresis is a technique in which the mechanical effects of ultrasound are used to enhance percutaneous absorption of anti-inflammatory drugs e.g., cortisol, dexamethasone, and salicylates and local analgesics e.g., lidocaine through the skin to the underlying tissues.
• B. Phonophoresis uses electrical currents to drive drugs through the skin.
• C. Phonophoresis heats tissue to increase absorption of medications.
• D. Phonophoresis uses laser energy to deliver drugs.

Answer: (A)

Phonophoresis uses ultrasound to push topical medications through the skin by mechanical effects. The ultrasound creates cavitation and acoustic streaming that transiently disrupt the outer skin layers, increasing permeability so drugs like anti-inflammatory agents (e.g., hydrocortisone, dexamethasone, salicylates) and local anesthetics (e.g., lidocaine) reach deeper tissues. This is different from iontophoresis, which relies on electrical currents to drive drugs through the skin, and from methods that rely primarily on heating or laser energy.