Which route of medication administration allows for continuous absorption over several hours?

The transdermal route of medication administration is designed to provide a continuous and sustained release of medication over several hours or even days. This method involves applying a patch that contains the medication directly onto the skin, allowing it to be absorbed slowly through the skin into the bloodstream. As the medication is released steadily, it maintains more stable drug levels in the body, which can improve efficacy and minimize side effects.

In contrast, the buccal and sublingual routes, while they allow for quick absorption into the bloodstream through the oral mucosa, are designed for rapid onset of action rather than prolonged release. The intramuscular route provides quicker absorption than oral routes, but the effects are typically shorter-lived compared to transdermal administration. Thus, the transdermal route is specifically designed for continuous absorption, making it the most suitable choice for this question.