Neurology: entacapone mechanism: practice question

A General Medicine 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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General Medicine · Neurology: entacapone mechanism

Sample item

A man with Parkinson disease on levodopa-carbidopa has end-of-dose wearing-off. Adding entacapone helps by which mechanism?

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

The answer and the reasoning

A. Inhibiting peripheral COMT to prolong levodopa action

Entacapone inhibits catechol-O-methyltransferase, reducing peripheral breakdown of levodopa to 3-O-methyldopa. This lengthens levodopa action and reduces off time. Dopamine agonists stimulate receptors directly.

Option by option

  • A. Inhibiting peripheral COMT to prolong levodopa action (correct)

    Correct. COMT inhibition extends levodopa exposure and reduces wearing-off.

  • B. Inhibiting monoamine oxidase type A

    MAO-B, not MAO-A, inhibition is used in Parkinson disease, by selegiline.

  • C. Blocking central muscarinic cholinergic receptors

    Muscarinic blockade is the action of anticholinergics such as trihexyphenidyl.

  • D. Directly stimulating striatal D2 receptors as an agonist

    Direct D2 stimulation is the action of agonists such as pramipexole.

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 General Medicine question

What is the answer to this General Medicine question?

The best answer is A, Inhibiting peripheral COMT to prolong levodopa action. Entacapone inhibits catechol-O-methyltransferase, reducing peripheral breakdown of levodopa to 3-O-methyldopa.

Why is "Inhibiting monoamine oxidase type A" not the answer?

MAO-B, not MAO-A, inhibition is used in Parkinson disease, by selegiline.

Why is "Blocking central muscarinic cholinergic receptors" not the answer?

Muscarinic blockade is the action of anticholinergics such as trihexyphenidyl.

Why is "Directly stimulating striatal D2 receptors as an agonist" not the answer?

Direct D2 stimulation is the action of agonists such as pramipexole.

What concept does this question test?

It tests Neurology: entacapone mechanism in General Medicine. This lengthens levodopa action and reduces off time. Dopamine agonists stimulate receptors directly.

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 Neurology: entacapone mechanism?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine 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.