Which option best describes the onset and control for topical administration?

• A. Fast onset with high control
• B. Slow onset with poor control
• C. Immediate onset
• D. Variable onset

Answer: (B)

The main idea is that topical administration often acts locally and must pass through the skin barrier, which slows both how quickly effects appear and how predictable the amount of drug exposure will be. The skin’s outer layer, the stratum corneum, limits absorption, and absorption varies greatly with site, thickness, hydration, condition of the skin, and the formulation used. Because of this variability, the onset is usually gradual rather than immediate, and the extent and timing of the effect are not easily controlled. While some routes deliver rapid and well-controlled effects, topical applications typically do not, making slow onset with poor control the best description.