Which term means crossing through the skin?

• A. Syndrome
• B. Therapeutic
• C. Toxic
• D. Transdermal

Answer: (D)

Transdermal describes something that passes across the skin. When a medication is delivered transdermally, it moves through the skin layers into the bloodstream to produce systemic effects, as with a transdermal patch. This is different from topical use, which targets the skin surface for a local effect. The other terms don’t fit because syndrome refers to a cluster of signs and symptoms, therapeutic relates to treatment, and toxic means poisonous or harmful.