Pharmacogenetics: plasma cholinesterase deficiency: 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.

Try it

Pharmacology · Pharmacogenetics: plasma cholinesterase deficiency

Sample item

A 35-year-old man remains apnoeic for 3 hours after succinylcholine for appendicectomy. His brother had a similar episode. He is haemodynamically stable with a normal temperature. What is the most appropriate management?

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

The answer and the reasoning

B. Continued ventilation with sedation until spontaneous recovery

Succinylcholine is normally hydrolysed within minutes by plasma pseudocholinesterase. Genetic variants with an atypical enzyme cause prolonged paralysis. Treatment is supportive, with ventilation and sedation until the block wears off. Neostigmine inhibits cholinesterase and would prolong the depolarising block.

Option by option

  • A. Intravenous dantrolene

    Dantrolene treats malignant hyperthermia, which has rigidity and hypercarbia, not flaccid apnoea.

  • B. Continued ventilation with sedation until spontaneous recovery (correct)

    Correct. Supportive ventilation with sedation is the standard care until the block wears off; purified cholinesterase or fresh frozen plasma can hasten recovery.

  • C. Intravenous sugammadex

    Sugammadex encapsulates rocuronium and vecuronium and does not reverse succinylcholine.

  • D. Intravenous neostigmine to reverse the block

    Neostigmine inhibits cholinesterase, further delaying succinylcholine breakdown.

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.

More Pharmacology questions

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is B, Continued ventilation with sedation until spontaneous recovery. Succinylcholine is normally hydrolysed within minutes by plasma pseudocholinesterase.

Why is "Intravenous dantrolene" not the answer?

Dantrolene treats malignant hyperthermia, which has rigidity and hypercarbia, not flaccid apnoea.

Why is "Intravenous sugammadex" not the answer?

Sugammadex encapsulates rocuronium and vecuronium and does not reverse succinylcholine.

Why is "Intravenous neostigmine to reverse the block" not the answer?

Neostigmine inhibits cholinesterase, further delaying succinylcholine breakdown.

What concept does this question test?

It tests Pharmacogenetics: plasma cholinesterase deficiency in Pharmacology. Genetic variants with an atypical enzyme cause prolonged paralysis. Treatment is supportive, with ventilation and sedation until the block wears off. Neostigmine inhibits cholinesterase and would prolong the depolarising block.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Pharmacogenetics: plasma cholinesterase deficiency?

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.