In adhesive-type transdermal DDS, how many of the following statements are correct?

• A. ALL statements are correct
• B. ONLY ONE statement is correct
• C. TWO statements are correct
• D. THREE statements are correct

Answer: (A)

In adhesive-type transdermal patches, the drug is incorporated directly into the adhesive layer that sticks the patch to the skin, so release and delivery are governed by diffusion through that adhesive into the skin. This design often uses a backing layer to prevent loss of drug from the top side and a protective liner that is removed before application. The rate at which the drug reaches systemic circulation is influenced by how well the drug dissolves in the adhesive, how quickly it diffuses through the adhesive, and how readily it partitions into the skin, with permeation enhancers sometimes added to boost flux. Because the system aims for a predictable, sustained release over the wear period, features like uniform drug distribution in the adhesive, biocompatibility and adequate adhesion, and appropriate wear-time performance are all aligned. If the statements describe these common characteristics—drug-in-adhesive formulation, presence of backing and liner, factors affecting release and permeation, and design for consistent dosing—they tend to be true together. That’s why selecting that all statements are correct is the best choice.