Which system delivers drugs through the skin for a systemic effect?

The correct answer is transdermal, as this method is specifically designed to deliver medications into the bloodstream through the skin, allowing for a systemic effect. Transdermal systems use adhesive patches containing drugs that can be absorbed through the skin over a prolonged period. This delivery method bypasses the gastrointestinal tract, which can enhance absorption and maintain more consistent drug levels in the bloodstream.

Transdermal delivery is particularly useful for medications that require a steady release over time or for drugs that have a high first-pass metabolism when taken orally. Common examples include patches for hormone replacement therapy, nicotine replacement, and pain relief.

In contrast, subcutaneous administration refers to injecting a drug into the fatty tissue beneath the skin, while intradermal refers to delivering a drug into the dermis layer of the skin. Both of these methods involve direct administration and are used for localized effects or for vaccines and allergy testing. Percutaneous absorption, while it sounds similar to transdermal, primarily refers to drug absorption through the skin that may not necessarily aim for a systemic effect. Therefore, the distinction lies in transdermal’s specific intent for systemic drug delivery.