Nokea
Intravenous administration of epinephrine to a patient results in a severe decrease in diastolic pressure and an increase in cardiac output. Which of the following drugs might the patient have previously taken that could account for this unexpected effect?
Correct Answer: D
Rationale: The correct answer is D: Prazosin. Prazosin is an alpha-1 adrenergic receptor antagonist, which blocks the vasoconstrictor effect of catecholamines like epinephrine, leading to vasodilation and a decrease in diastolic pressure. The unexpected effect of a decrease in diastolic pressure and an increase in cardiac output after epinephrine administration suggests that the patient might have taken a drug that blocks alpha-1 receptors. Propranolol (A) is a beta-blocker, which would not cause this effect. Atropine (B) is a muscarinic receptor antagonist and would not explain the observed effects. Phenylephrine (C) is an alpha-1 agonist, so it would not result in the described response. Therefore, Prazosin (D) is the most likely drug the patient previously took to account for the unexpected effects of epinephrine administration.