CNS drugs and antiepileptics: ziconotide: 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 · CNS drugs and antiepileptics: ziconotide

Sample item

A patient with refractory cancer pain receives an intrathecal infusion of a peptide derived from the venom of a marine cone snail. Which channel does it block?

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

The answer and the reasoning

C. N-type voltage-gated calcium channel

Ziconotide is a synthetic form of omega-conotoxin that blocks N-type calcium channels on nociceptive afferents in the dorsal horn. It is given intrathecally for severe refractory pain, and psychiatric and neurological adverse effects limit its use. It is not an opioid, so there is no respiratory depression or tolerance.

Option by option

  • A. NMDA receptor channel

    NMDA channel block is the action of ketamine.

  • B. Mu opioid receptor-coupled potassium channel

    Opioid receptor activation is the action of intrathecal morphine, not of ziconotide.

  • C. N-type voltage-gated calcium channel (correct)

    Correct. Ziconotide blocks N-type calcium channels in the spinal cord.

  • D. Voltage-gated sodium channel Nav1.7

    Sodium channel block is the action of local anaesthetics.

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 C, N-type voltage-gated calcium channel. Ziconotide is a synthetic form of omega-conotoxin that blocks N-type calcium channels on nociceptive afferents in the dorsal horn.

Why is "NMDA receptor channel" not the answer?

NMDA channel block is the action of ketamine.

Why is "Mu opioid receptor-coupled potassium channel" not the answer?

Opioid receptor activation is the action of intrathecal morphine, not of ziconotide.

Why is "Voltage-gated sodium channel Nav1.7" not the answer?

Sodium channel block is the action of local anaesthetics.

What concept does this question test?

It tests CNS drugs and antiepileptics: ziconotide in Pharmacology. It is given intrathecally for severe refractory pain, and psychiatric and neurological adverse effects limit its use. It is not an opioid, so there is no respiratory depression or tolerance.

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: ziconotide?

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.