CNS drugs and antiepileptics: pregabalin mechanism: 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 · CNS drugs and antiepileptics: pregabalin mechanism

Sample item

A patient with post-herpetic neuralgia is started on pregabalin. Through which target does it reduce neuropathic pain?

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

The answer and the reasoning

D. The alpha-2-delta subunit of presynaptic voltage-gated calcium channels

Pregabalin and gabapentin bind the alpha-2-delta subunit of voltage-gated calcium channels, reducing calcium entry and the release of glutamate and substance P. Despite being GABA analogues, they do not act on GABA receptors. Dizziness, sedation and weight gain are common adverse effects.

Option by option

  • A. Inactivation of voltage-gated sodium channels

    Sodium channel inactivation is the action of phenytoin and carbamazepine.

  • B. Inhibition of GABA transaminase

    GABA transaminase inhibition is the action of vigabatrin.

  • C. Positive allosteric modulation of the GABA-A receptor

    GABA-A receptor modulation is the action of benzodiazepines, not of pregabalin.

  • D. The alpha-2-delta subunit of presynaptic voltage-gated calcium channels (correct)

    Correct. Binding alpha-2-delta reduces calcium influx and excitatory transmitter release.

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, The alpha-2-delta subunit of presynaptic voltage-gated calcium channels. Pregabalin and gabapentin bind the alpha-2-delta subunit of voltage-gated calcium channels, reducing calcium entry and the release of glutamate and substance P.

Why is "Inactivation of voltage-gated sodium channels" not the answer?

Sodium channel inactivation is the action of phenytoin and carbamazepine.

Why is "Inhibition of GABA transaminase" not the answer?

GABA transaminase inhibition is the action of vigabatrin.

Why is "Positive allosteric modulation of the GABA-A receptor" not the answer?

GABA-A receptor modulation is the action of benzodiazepines, not of pregabalin.

What concept does this question test?

It tests CNS drugs and antiepileptics: pregabalin mechanism in Pharmacology. Despite being GABA analogues, they do not act on GABA receptors. Dizziness, sedation and weight gain are common adverse effects.

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 CNS drugs and antiepileptics: pregabalin mechanism?

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.