A newly diagnosed hypertensive patient is started on prazosin,an alpha adrenergic blocker.Within the hour,he complains of dizziness and loses consciousness.What has happened?
A) The drug activated the baroreceptors, causing an intense parasympathetic discharge, and thereby increasing blood pressure and precipitating a mild stroke.
B) The prazosin decreased his blood pressure too much; the drug-induced hypotension caused the fainting event (syncope).
C) The prazosin caused spasm of the cerebral blood vessels, which, in turn, caused loss of consciousness.
D) The patient experienced a hypertensive crisis.

Question

Quizplus · Accepted Answer

Prazosin is an alpha-adrenergic blocker that works by blocking the alpha1 receptors on blood vessels, resulting in vasodilation and decreased blood pressure. In a newly diagnosed hypertensive patient, prazosin may cause a sudden drop in blood pressure, especially if the dose is too high. This can lead to dizziness and fainting (syncope). It is important to monitor blood pressure closely and adjust the dose accordingly to prevent this side effect. Option A is incorrect because activation of baroreceptors leads to a decrease in sympathetic activity and increase in parasympathetic activity, which would have the opposite effect of increasing blood pressure. Option C is incorrect because prazosin causes vasodilation and would not lead to cerebral vessel spasm. Option D is incorrect because hypertensive crisis is a sudden and severe increase in blood pressure, not a decrease.

A Newly Diagnosed Hypertensive Patient Is Started on Prazosin,an Alpha