Which of the following drugs is classified as a Schedule II drug?

Alfentanil is classified as a Schedule II drug due to its high potential for abuse and its accepted medical use. Schedule II drugs are substances that have a high potential for addiction and severe physiological or psychological dependence. Alfentanil, an opiate used primarily for anesthesia and pain management, falls into this category because it can lead to significant levels of dependence when misused.

On the other hand, dronabinol is classified as a Schedule III drug, which indicates a lower potential for abuse compared to Schedule II substances. Testosterone likewise is classified as a Schedule III drug since it has recognized medical properties but still poses risks for abuse, although those risks are lower than those associated with Schedule II drugs. Codeine preparations may vary in classification; those with lower amounts of codeine can be classified as Schedule III or V, depending on their composition and concentration.

Thus, the classification of alfentanil as a Schedule II drug is aligned with the guidelines for substances that are highly regulated due to their potential for abuse and the dangers associated with misuse.