What is a major drawback of IV administration?

• A. Risk of toxicity since drug cannot be removed
• B. No lag time
• C. Ability to recall drug instantly
• D. Only small volumes can be given

Answer: (A)

Direct entry into the bloodstream gives 100% bioavailability and a rapid onset, but that immediacy is a double-edged sword. Because the drug is delivered straight into systemic circulation, there’s little time for the body to buffer the dose, and first-pass mechanisms can’t reduce exposure. If the dose is too high or the patient is especially sensitive, plasma concentrations can spike quickly, leading to toxicity. Stopping the infusion can slow further input, but it cannot instantly remove the drug already in the bloodstream; elimination by the body takes time, and in some cases reversal requires antidotes or specialized support.

The other statements aren’t the same kind of drawback. No lag time describes rapid onset (a strength, not a drawback). The notion of recalling a drug instantly isn’t a real pharmacologic concept relevant to IV therapy. And IV administration can accommodate larger volumes, not just small ones, so volume as a general limitation isn’t universal.

So the major drawback is the heightened risk of toxicity from having the drug enter circulation immediately without the buffering steps seen with other routes.