Autonomic nervous system: ganglion blockers: practice question

A Pharmacology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pharmacology · Autonomic nervous system: ganglion blockers

Sample item

A drug that blocks nicotinic receptors at all autonomic ganglia, such as hexamethonium, is given to a volunteer in a study. Which set of effects is expected?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Postural hypotension, dry mouth, constipation and urinary retention

Ganglion blockade removes both sympathetic and parasympathetic outflow. The effect seen in each organ is that of the dominant tone, so vessels dilate and cause postural hypotension, while the gut, bladder and salivary glands lose parasympathetic drive. This lack of selectivity is why the drugs are obsolete.

Option by option

  • A. Fasciculations, muscle paralysis and hyperkalaemia

    Fasciculation and hyperkalaemia belong to depolarising blockade at the neuromuscular junction.

  • B. Postural hypotension, dry mouth, constipation and urinary retention (correct)

    Correct. Loss of dominant vascular sympathetic tone and of parasympathetic drive to the gut, bladder and glands.

  • C. Bradycardia, miosis, salivation and diarrhoea

    This pattern describes excess parasympathetic activity, as with a cholinesterase inhibitor.

  • D. Hypertension, sweating, tremor and tachycardia

    This describes sympathetic overactivity, the opposite of ganglion blockade.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is B, Postural hypotension, dry mouth, constipation and urinary retention. Ganglion blockade removes both sympathetic and parasympathetic outflow.

Why is "Fasciculations, muscle paralysis and hyperkalaemia" not the answer?

Fasciculation and hyperkalaemia belong to depolarising blockade at the neuromuscular junction.

Why is "Bradycardia, miosis, salivation and diarrhoea" not the answer?

This pattern describes excess parasympathetic activity, as with a cholinesterase inhibitor.

Why is "Hypertension, sweating, tremor and tachycardia" not the answer?

This describes sympathetic overactivity, the opposite of ganglion blockade.

What concept does this question test?

It tests Autonomic nervous system: ganglion blockers in Pharmacology. The effect seen in each organ is that of the dominant tone, so vessels dilate and cause postural hypotension, while the gut, bladder and salivary glands lose parasympathetic drive. This lack of selectivity is why the drugs are obsolete.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Autonomic nervous system: ganglion blockers?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.