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USMLE (United States Medical Licensing Examination) Practice Exam 05

Practice exam for USMLE (United States Medical Licensing Examination).

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Question 1 of 1000%

Time remaining120:00

Attempts allowedUnlimited

Difficulty mixE • M • H

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Question 1

MEDIUM

120:00

A 72-year-old man with chronic obstructive pulmonary disease is started on a new medication for lower urinary tract symptoms due to benign prostatic hyperplasia. Two hours after the first dose, he develops lightheadedness when standing. Blood pressure is 128/76 mm Hg supine and 96/60 mm Hg standing; heart rate increases from 72/min to 96/min. Which mechanism best explains this adverse effect?

Alpha-1 antagonists used for BPH (eg, tamsulosin, doxazosin) can cause orthostatic hypotension via vasodilation from alpha-1 blockade in peripheral vascular smooth muscle.

Select one answer

Blockade of alpha-1 receptors in vascular smooth muscle causing decreased peripheral resistance

Inhibition of acetylcholinesterase causing increased vagal tone

Blockade of beta-1 receptors in the heart causing reduced contractility

Activation of alpha-2 receptors in the brainstem causing decreased sympathetic outflow

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USMLE (United States Medical Licensing Examination) Practice Exam 05

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