The same drug may have different effects when administered by different routes.

• A. True
• B. False
• C. Sometimes
• D. Never

Answer: (A)

The key idea here is that how a drug enters the body changes how much of it is available at the site of action and how quickly it gets there. The route of administration determines absorption, bioavailability, and the time course of drug levels in the body. Because of this, the same chemical can produce different effects when given by different routes.

For example, delivering a drug intravenously puts it directly into the bloodstream, producing a rapid onset and full systemic exposure with predictable intensity. Giving the same drug by mouth, however, subjects it to stomach acid, intestinal walls, and especially liver metabolism before it ever reaches systemic circulation (the first-pass effect). That can reduce the amount that becomes active or changes how quickly and strongly it acts. Other routes can emphasize local effects (such as a topical ointment acting on the skin) versus systemic effects (like a transdermal patch designed for steady systemic release). Absorption rate, distribution to tissues, and metabolism all shift with the route, so the overall effect can be stronger, weaker, faster, slower, or even qualitatively different.

That’s why the statement is true: the same drug may have different effects when administered by different routes. In practice, this is a fundamental consideration in dosing and selecting the route to achieve the desired effect while minimizing adverse outcomes.