Which of the following can only be given IV?

• A. Ketamine
• B. Propofol
• C. Alpha 2 agonists
• D. Opioids

Answer: (B)

Propofol is the intravenous-only agent because of how it’s formulated and how it behaves in the body. It is prepared as an oil-in-water emulsion and has very rapid onset and offset when delivered by IV infusion or bolus, allowing precise control of anesthesia induction and maintenance. Its absorption from other routes is unreliable: if given intramuscularly or by other non-IV routes, the bioavailability is unpredictable and the onset is too slow for safe induction. Oral administration is not practical due to poor bioavailability and first-pass metabolism, so it isn’t used that way in clinical practice.

In contrast, the other options can be given by multiple routes. Ketamine can be given IV or IM; alpha-2 agonists are commonly given IV and can also be used intramuscularly in many protocols; opioids have IV, IM, subcutaneous, and other routes. Thus, propofol stands out as the agent typically used exclusively by the IV route.