QuestionSBA
QuestionChoice
This is correct. Competitive antagonists bind to the same receptor site as the agonist (opioid molecules in this case) but do not activate it, thus blocking the agonist's action.
10026020
a
Competitive antagonist
QuestionChoice
This is incorrect. An agonist would bind to the receptor and activate it. Naloxone does not activate the receptor and thus is not an agonist.
10026022
c
Agonist
QuestionChoice
This is incorrect. A non-competitive antagonist prevents the activation of a receptor by binding to an allosteric (non-agonist) site on the receptor. Because naloxone binds to the same receptor site as the opioid molecules, it is not a non-competitive antagonist.
10026021
b
Non-competitive antagonist
QuestionChoice
This is incorrect. A negative allosteric modulator would lower the affinity/efficacy of the agonist. Naloxone binds to the same receptor site as opioid molecules and does not activate the receptor, making it a competitive antagonist and not a negative allosteric modulator.
10026024
e
Negative allosteric modulator
QuestionChoice
This is incorrect. A positive allosteric modulator would increase the affinity and/or efficacy of the agonist. Naloxone prevents the agonist from binding to the receptor, so it is not a positive allosteric modulator. It is a competitive antagonist.
10026023
d
Positive allosteric modulator
Concept
Chapter
2693
5873
Types of antagonists
Topic
166
General pharmacological concepts
17602
A woman is brought into the emergency department by ambulance after being found unresponsive with a low respiratory rate. On examination, she has pinpoint pupils.

Opioid overdose is suspected, and she is given naloxone. The clinician explains that naloxone acts on the same receptor site as opioid molecules but does not activate the receptor.

Which of the following terms best describes the mechanism of action of naloxone?
a