What is the role of opioids in pain management?

• A. Inhibit reuptake of serotonin
• B. Block prostaglandin synthesis
• C. Bind opioid receptors to block pain signals for moderate to severe pain
• D. Increase pain sensitivity

Answer: (C)

Opioids relieve pain by binding to opioid receptors in the brain and spinal cord, especially mu receptors, which dampen the transmission of pain signals and alter the perception of pain. This receptor activation reduces the release of nociceptive neurotransmitters and hyperpolarizes neurons in pain pathways, producing analgesia. Because this mechanism directly modulates the pathways that carry and interpret pain, opioids are particularly effective for moderate to severe pain, such as postoperative or cancer-related pain. The other options describe actions not characteristic of opioids: inhibiting serotonin reuptake is typical of certain antidepressants, blocking prostaglandin synthesis is the action of NSAIDs, and increasing pain sensitivity would worsen pain rather than relieve it (though rare forms of opioid-induced hyperalgesia can occur with long-term use).