## **Core Concept**
Transdermal drug delivery systems (TDDS) are designed to deliver drugs through the skin for systemic effects. The primary advantages of TDDS include improved patient compliance, avoidance of first-pass metabolism, and more consistent drug plasma levels.

## **Why the Correct Answer is Right**
The correct answer, , likely represents an option that does not align with the known benefits of transdermal drug delivery. Common advantages of TDDS include enhanced bioavailability, reduced side effects, and ease of use.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Likely represents an advantage such as improved patient compliance, which is a well-known benefit of TDDS.
- **Option B:** Probably mentions avoidance of first-pass metabolism, another significant advantage of transdermal delivery.
- **Option C:** Could represent a benefit like sustained release of the drug, providing a more consistent plasma concentration.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that not all drugs are suitable for transdermal delivery; the drug must have specific physicochemical properties (e.g., lipophilicity, molecular size) to effectively permeate the skin.

## **Correct Answer:** . First-pass metabolism is avoided but it can cause skin irritation.