A 34-year-old woman underwent magnetic resonance imaging (MRI) to investigate an acoustic neuroma. Because the woman had had a mild allergic reaction to contrast media in the past, she was given a prescription for drugs to be taken before the MRI. Which of the following drugs should be included in that prescription?

Correct Answer: D

Rationale: The correct answer is D: Diphenhydramine. Diphenhydramine is a first-generation antihistamine that can help prevent allergic reactions to contrast media. It works by blocking the action of histamine, which is released during allergic reactions. This drug is commonly used for pre-medication to prevent allergic reactions to contrast media in patients with a history of mild reactions. Choice A (Fluorocortisone) is a corticosteroid and is not typically used for preventing allergic reactions to contrast media. Choice B (Famotidine) is a histamine-2 blocker used for stomach acid reduction and is not indicated for preventing allergic reactions. Choice C (Zafirlukast) is a leukotriene receptor antagonist used for asthma and allergies, but it is not typically used for pre-medication before MRI with contrast media.

Correct Answer: B

Rationale: The correct answer is B: Trigeminal nerve. Sumatriptan is a serotonin receptor agonist that acts on serotonin receptors in the trigeminal nerve to reduce inflammation and pain associated with migraines. The trigeminal nerve is a key player in the pathophysiology of migraines, transmitting pain signals from blood vessels and meninges to the brain. The other choices (A: Nucleus accumbens, C: Vestibular nuclei, D: Chemoreceptor trigger zone) are not directly involved in the pathophysiology of migraines or the mechanism of action of sumatriptan. The nucleus accumbens is primarily associated with reward and motivation, the vestibular nuclei are involved in balance and spatial orientation, and the chemoreceptor trigger zone is related to the regulation of vomiting.

Correct Answer: D

Rationale: Most drugs are absorbed in the GI tract via passive diffusion (Choice D), driven by lipid solubility and concentration gradients across membranes. Active transport (Choice A) requires energy, filtration (Choice B) is minor for drugs, and endocytosis/exocytosis (Choice C) is rare for small molecules.

Correct Answer: B

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.