Which statement about reservoir-type transdermal patches is true?

• A. It can be divided to adjust dose.
• B. It cannot be divided because dividing would release the dose immediately.
• C. It uses adhesive matrix.
• D. It requires an external energy source to drive release.

Answer: (B)

Reservoir-type patches deliver the drug through a sealed reservoir that is separated from the skin by a rate-controlling barrier. The amount of drug that reaches the skin is governed by that barrier, giving a steady release over time. If the patch were divided, the barrier would be breached or the reservoir would be exposed differently, causing a rapid, uncontrolled release of the drug rather than the intended slow, controlled delivery. That’s why dividing the patch is not appropriate and why the statement about division releasing the dose immediately is the best fit.

In contrast, these patches aren’t based on the drug being in an adhesive matrix, and there’s no need for an external energy source—the release is driven by diffusion through the rate-controlling barrier.