Acetic acid iontophoresis is used to treat calcific deposits and is delivered using which polarity?

• A. Positive polarity
• B. Alternating polarity
• C. Negative polarity
• D. Direct current with a fixed polarity

Answer: (C)

Iontophoresis moves charged ions into tissue using direct current, and the direction depends on the ion’s charge. Acetic acid, when ionized, forms acetate ions that are negatively charged. To drive these negative ions into the calcific deposits, the treatment area is placed under the negative polarity, so the negative ions are repelled from the electrode into the tissue. Using alternating polarity wouldn’t sustain net delivery, and using the positive polarity would repel the negatively charged ions away rather than into the tissue. Direct current with fixed polarity is the method, but the key point is that the ion’s negative charge requires negative polarity.