NCLEX-RN : Pharmacology

Study concepts, example questions & explanations for NCLEX-RN

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Example Questions

Example Question #191 : Nclex

You are the nurse in a primary care clinic taking care of a patient with spastic bladder. Her physician prescribes oxybutynin for symptom relief. Which of the following best describes the mechanism of action of oxybutynin?

Possible Answers:

Antagonism of M1, M2, and M3 muscarinic acetylcholine receptors

Alpha-adrenergic blockade

Beta-adrenergic blockade

Direct thrombin inhibition

Calcium-channel blockade

Correct answer:

Antagonism of M1, M2, and M3 muscarinic acetylcholine receptors

Explanation:

The correct answer is "Antagonism of M1, M2, and M3 muscarinic acetylcholine receptors."

This is the correct answer because it accurately describes the way in which oxybutynin exhibits its anticholinergic properties, which help to relieve urinary frequency/urgency and bladder spasm. In patients with spastic bladder, oxybutynin exhibits its anticholinergic effects most significantly on the smooth muscle of the bladder detrusor muscle, which helps to treat the patients' symptoms associated with spasm of the muscle, which often manifests as urinary frequency or urgency, with or without urinary incontinence. 

Calcium-channel blockade does not describe the mechanism of action of oxybutynin. Verapamil and amlodipine are examples of calcium-channel blockers.

Beta-adrenergic blockade does not describe the mechanism of action of oxybutynin. Propranolol and esmolol are examples of beta-adrenergic blockers.

Alpha-adrenergic blockade does not describe the mechanism of action of oxybutynin. Tamsulosin and doxazosin are examples of alpha-adrenergic blockers.

Direct thrombin inhibition does not describe the mechanism of action of oxybutynin. Argatroban and lepirudin are examples of direct thrombin inhibitors.

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