A43-year-old woman complained to her physician of annoying daytime sleepiness. The woman, who was treated in the past with several drugs for generalized anxiety, had been receiving diazepam for the past month. One week ago, she started taking an over-the-counter preparation for seasonal allergic rhinitis. Which of the following drugs most likely precipitated the patient's daytime sleepiness?

Correct Answer: C

Rationale: Step-by-step rationale for why choice C (Diphenhydramine) is correct: 1. Diphenhydramine is a first-generation antihistamine known for causing sedation. 2. The patient was experiencing daytime sleepiness, a common side effect of diphenhydramine. 3. The combination with diazepam (a sedative) likely potentiated the sedative effects. 4. Loratadine (choice A) is a non-sedating antihistamine. 5. Prednisone (choice B) is a corticosteroid and not typically associated with sedation. 6. Zolpidem (choice D) is a sedative-hypnotic used for insomnia but not taken by the patient.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.