Which of the following is an example of an opiate antagonist?

Naloxone is considered an opiate antagonist because it works by binding to the same receptors in the brain as opiates, but instead of activating them, it blocks their effects. This property makes naloxone especially valuable in reversing the effects of opioid overdoses, as it can quickly restore normal breathing and consciousness in individuals who have consumed an excessive amount of opiates.

In contrast, buprenorphine is a partial agonist, which means it activates opioid receptors but to a lesser degree compared to full agonists like morphine and codeine. Morphine and codeine are both full agonist opioids that provide pain relief by activating opioid receptors, so they do not have antagonist properties. This understanding of how different substances interact with opioid receptors is crucial for effectively managing addiction and overdose situations.