Which statement about mecholyl in iontophoresis is true?

• A. It produces a more intense local counterirritation
• B. It is deposited in deeper layers of the skin and absorbed gradually
• C. Systemic effects occur in most cases
• D. It gives best results only in non-ulcer conditions

Answer: (B)

Mecholyl (methacholine) delivered by iontophoresis is moved into the skin using an electric current because it carries a positive charge. The electrical field pushes the drug into the deeper layers of the skin, and once there it diffuses slowly into the bloodstream. That combination—deeper deposition with gradual absorption—fits how iontophoresis delivers this drug and explains why this statement is true. Systemic effects aren’t typical in most cases because the amount reaching the circulation is limited and released gradually. It isn’t about causing stronger local irritation, and its effectiveness isn’t limited to non-ulcer conditions; ulceration can unpredictably alter absorption, so claiming it works best only in non-ulcer conditions isn’t accurate.