Absorption rates are, in part, determined by route of administration. Why would one drug be given intravenously and another via transdermal patch with reference to plasma levels, the therapeutic window and dosing?
The correct answer and explanation is:
Correct Answer:
Drugs are given by different routes such as intravenous or transdermal to control the speed and consistency of absorption, maintain plasma levels within the therapeutic window, and manage dosing frequency.
Explanation:
The route of drug administration plays a key role in how fast and how much of a drug reaches the bloodstream. Intravenous (IV) administration involves injecting the drug directly into the bloodstream. This allows for immediate absorption, leading to rapid onset of action and precise control of plasma concentration. IV drugs are especially useful in emergencies or when immediate therapeutic effects are needed. They help maintain plasma levels within the therapeutic window more predictably, especially for drugs with narrow therapeutic ranges. However, because IV administration leads to high peak levels quickly, it can also increase the risk of toxicity if not properly monitored.
On the other hand, a transdermal patch delivers medication slowly through the skin into the bloodstream over an extended period. This route is chosen when a slow, steady release of the drug is preferred. It helps maintain stable plasma levels within the therapeutic window and reduces the risk of spikes or drops in concentration that can lead to side effects or subtherapeutic effects. Transdermal patches are convenient for patients, especially when long-term, consistent dosing is required. They also improve compliance since the dosing frequency is often once daily or even less frequent.
In summary, intravenous delivery is chosen for immediate, controlled plasma levels with rapid action, while transdermal patches are used for sustained release, stable plasma concentration, and ease of use. Both routes aim to keep the drug concentration within the therapeutic window for effective and safe treatment.