Antipsychotics: neuroleptic malignant syndrome: 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 · Antipsychotics: neuroleptic malignant syndrome

Sample item

A 30-year-old man started on haloperidol a week ago develops temperature 40 degrees Celsius, generalised lead-pipe rigidity, diaphoresis and fluctuating consciousness over two days. Creatine kinase is 15,000 U/L and reflexes are normal. After stopping haloperidol and starting cooling and fluids, which drug is appropriate to add?

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

The answer and the reasoning

D. Dantrolene

This is neuroleptic malignant syndrome, caused by central dopamine D2 blockade, with slow onset, rigidity and normal or reduced reflexes. After stopping the antipsychotic, supportive care and muscle relaxation with dantrolene or dopamine agonist bromocriptine are used. Cyproheptadine treats serotonin syndrome, which features hyperreflexia and clonus with rapid onset.

Option by option

  • A. Intravenous benztropine as sole therapy

    Benztropine alone does not treat the hypermetabolic rigidity and can worsen hyperthermia through reduced sweating.

  • B. Cyproheptadine

    Cyproheptadine is for serotonin syndrome, which shows clonus and hyperreflexia rather than lead-pipe rigidity.

  • C. Haloperidol at a reduced dose

    Reducing the dose of the causative D2 blocker would perpetuate the syndrome; it must be stopped.

  • D. Dantrolene (correct)

    Dantrolene reduces skeletal muscle heat production and rigidity in this syndrome.

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 D, Dantrolene. This is neuroleptic malignant syndrome, caused by central dopamine D2 blockade, with slow onset, rigidity and normal or reduced reflexes.

Why is "Intravenous benztropine as sole therapy" not the answer?

Benztropine alone does not treat the hypermetabolic rigidity and can worsen hyperthermia through reduced sweating.

Why is "Cyproheptadine" not the answer?

Cyproheptadine is for serotonin syndrome, which shows clonus and hyperreflexia rather than lead-pipe rigidity.

Why is "Haloperidol at a reduced dose" not the answer?

Reducing the dose of the causative D2 blocker would perpetuate the syndrome; it must be stopped.

What concept does this question test?

It tests Antipsychotics: neuroleptic malignant syndrome in Pharmacology. After stopping the antipsychotic, supportive care and muscle relaxation with dantrolene or dopamine agonist bromocriptine are used. Cyproheptadine treats serotonin syndrome, which features hyperreflexia and clonus with rapid onset.

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 Antipsychotics: neuroleptic malignant syndrome?

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.