How does naloxone function in opioid overdose and what routes are used?

• A. Competitively displaces opioid at mu receptors; IV, IM, subcutaneous, intranasal routes.
• B. Acts as an opioid receptor agonist to reverse effects.
• C. Inhibits opioid metabolism.
• D. Only reverses respiratory depression when given IV.

Answer: (A)

Naloxone acts as a competitive antagonist at opioid receptors, especially mu receptors. By binding with high affinity, it displaces opioids from these receptors and rapidly reverses opioid-induced effects such as sedation and respiratory depression. It does not stimulate receptors (not an agonist) and it doesn’t inhibit opioid metabolism; it simply blocks receptor activity temporarily. For administration, it can be given by multiple routes: intravenous, intramuscular, subcutaneous, and intranasal, with intranasal use common in community settings and IV/IM used in hospital or EMS contexts. Because the duration of naloxone can be shorter than that of some opioids, repeated dosing or observation is often necessary after reversal.