Which of the following medications is most commonly used with iontophoresis to treat wrist tendinitis?

• A. Acetic acid
• B. Lidocaine
• C. Dexamethasone
• D. Magnesium

Answer: (C)

Iontophoresis works by using a mild electric current to push charged drug ions into the underlying tissue, so the medication chosen should be one that provides a meaningful anti-inflammatory effect at the tendon. For wrist tendinitis, reducing inflammation in the tendon sheath is the main goal, and a corticosteroid delivered iontophoretically is the most effective option. Dexamethasone (often as dexamethasone phosphate) is a potent anti-inflammatory steroid that is commonly prepared for iontophoretic delivery, making it the best answer for this application.

Acetic acid is typically used to address calcific deposits in tendons rather than active inflammation. Lidocaine can provide local pain relief but does not address the inflammatory process long term. Magnesium has less consistent evidence and is not a standard, widely chosen iontophoretic treatment for wrist tendinitis.