Pharmacology Autonomic Nervous System Agents 2

Question 1

A patient on prazosin for hypertension reports dizziness when standing up quickly. What is the mechanism behind this adverse effect?

Accepted Answer

Blockade of alpha-1 adrenergic receptors causing venous pooling

Answer

Prazosin blocks alpha-1 receptors in peripheral vasculature, reducing vascular tone and causing orthostatic hypotension from venous pooling.

Question 2

Which cholinomimetic agent is used to reverse non-depolarizing neuromuscular blockade and acts by inhibiting acetylcholinesterase?

Accepted Answer

Neostigmine

Answer

Neostigmine is a reversible acetylcholinesterase inhibitor used to reverse neuromuscular blockade by increasing ACh at the neuromuscular junction.

Question 3

A patient with pheochromocytoma is scheduled for surgery. Which drug class should be started FIRST to prevent hypertensive crisis during tumor manipulation?

Accepted Answer

Alpha-blockers before beta-blockers

Answer

Alpha-blockers (e.g., phenoxybenzamine) must be given before beta-blockers to prevent unopposed alpha-mediated vasoconstriction, which would worsen hypertension.

Question 4

Dobutamine is preferred over dopamine in cardiogenic shock primarily because it:

Accepted Answer

Selectively increases cardiac contractility with less peripheral vasoconstriction

Answer

Dobutamine predominantly stimulates beta-1 receptors, increasing contractility and cardiac output without the significant vasoconstriction seen with dopamine.

Question 5

Which antimuscarinic drug is preferred for treating bradycardia during surgery due to its minimal CNS penetration?

Accepted Answer

Glycopyrrolate

Answer

Glycopyrrolate is a quaternary ammonium compound that does not cross the blood-brain barrier, making it preferred over atropine when CNS effects are undesirable.

Pharmacology Practice Test

Pharmacology Practice Test

Pharmacology Autonomic Nervous System Agents 2