The effect of the drug on parasympathetic function declines rapidly in all organs, except?

RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Applied Anatomy

Medium

Appeared in: RUHS, Jaipur, M.Sc Nursing Entrance Exam-2018

Explanation

The question asks for the organ where the effects of a parasympathetic blocking drug (like atropine) do NOT decline rapidly.
The effects of atropine are most persistent in the eye.
When administered, atropine causes mydriasis (pupil dilation) and cycloplegia (paralysis of accommodation for near vision).
This is due to the strong and prolonged binding of the drug to muscarinic receptors in the iris and ciliary muscle.
These ocular effects can last for 7 to 10 days, far longer than the effects on other systems.

Option B: The effect of atropine on the heart, primarily tachycardia (increased heart rate), is transient. It depends on the systemic concentration of the drug, which declines rapidly as the drug is metabolized (half-life of 3-4 hours).
Option C: Atropine's effect on visceral smooth muscles, such as reducing gastrointestinal motility and relaxing the bladder, is also short-lived and corresponds with the drug's systemic half-life.
Option D: The effect on glands (salivary, sweat, lacrimal) is one of the most sensitive and most transient. Dry mouth and skin are common side effects that appear and resolve relatively quickly, within hours.

Clinical Relevance

Nursing practice connection: Knowing Differential duration of action of antimuscarinic drugs across various organs helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding the differential duration of action is critical for patient safety and education.
A nurse must advise a patient receiving atropine for an eye exam about the prolonged side effects of photophobia and blurred vision, which can last for over a week.
Safety instructions, such as avoiding driving and wearing sunglasses, are essential nursing interventions to prevent injury.

How to Approach the Question

First, identify the question type. This is a pharmacology recall question with a negative lead-in ('except').
The stem asks to identify the organ where the effect of a parasympathetic blocking drug does NOT decline rapidly.
This means you need to find the organ with the most prolonged or persistent effect.
Recall the actions of the prototype anticholinergic drug, Atropine, on different organ systems.
Compare the duration of action on the eye, heart, smooth muscle, and glands.
Select the organ with the longest-lasting effect, which is the eye (mydriasis and cycloplegia can last for days).

Concept Tested & Keywords

Concept Tested: Differential duration of action of antimuscarinic drugs across various organs.
Stem keywords: drug effect, parasympathetic function, declines rapidly
Lead-in keywords: except
Negative lead-in flag: The question asks for the exception, meaning the organ where the drug's effect persists the longest.

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