Naloxone and naltrexone are both opioid antagonists, meaning they block opioid receptors, but they differ in their use, administration, and duration of action. Here’s a concise comparison:

Naloxone:

• Purpose: Primarily used to reverse opioid overdoses (e.g., from heroin, fentanyl, or prescription opioids) by rapidly displacing opioids from receptors.
• Administration: Administered via injection (IV, IM, or subcutaneous) or nasal spray (e.g., Narcan).
• Onset and Duration: Acts within minutes (1–5 minutes) but has a short half-life (30–60 minutes), so effects wear off quickly.
• Use Case: Emergency treatment for acute opioid overdose; not used for long-term management.
• Availability: Often available over-the-counter or through first responders for emergency use.

Naltrexone:

• Purpose: Used to treat opioid use disorder and alcohol dependence by blocking opioid receptors, reducing cravings and the rewarding effects of opioids or alcohol.
• Administration: Taken orally (daily pill, e.g., Revia) or as a monthly intramuscular injection (e.g., Vivitrol).
• Onset and Duration: Slower onset; effects last much longer (24 hours for oral, up to 30 days for injectable).
• Use Case: Long-term management to prevent relapse in opioid or alcohol dependence, typically after detoxification.
• Availability: Prescription-only, requires medical supervision.

Key Differences:

• Urgency: Naloxone is for immediate, life-saving intervention; naltrexone is for maintenance therapy.
• Duration: Naloxone is short-acting; naltrexone is long-acting.
• Setting: Naloxone is used in emergencies; naltrexone is part of ongoing treatment plans.

Both drugs are critical in addressing opioid-related issues but serve distinct roles. If you have a specific context or question about their use, let me know!

Disclaimer: Grok is not a doctor; please consult one. Don’t share information that can identify you.