Fentanyl-blocking effects of extended-release naltrexone in humans: Three case reports

Area of Science:

• Pharmacology and Toxicology
• Addiction Medicine
• Clinical Research

Background:

• Fentanyl's role in the ongoing opioid overdose epidemic is a critical public health concern.
• Respiratory depression is a life-threatening side effect of µ-agonist opioids like fentanyl.
• Limited human data exists on the efficacy of extended-release naltrexone (ER-NTX) in blocking fentanyl's respiratory effects.

Purpose of the Study:

• To investigate the ability of extended-release naltrexone (ER-NTX) to counteract fentanyl-induced respiratory depression in humans.
• To present clinical case histories of patients undergoing opioid challenges while on ER-NTX.
• To provide the first human evidence of ER-NTX's effectiveness against lethal fentanyl doses.

Main Methods:

• Presentation of three case histories involving clinically indicated opioid challenges in patients with ER-NTX implants.
• Review of existing sparse literature on naltrexone and fentanyl interactions.
• Assessment of antagonist blood levels and their correlation with blocking µ-agonist effects.

Main Results:

• ER-NTX preparations achieved sufficient blood levels to completely block the lethal effects of at least 1,000 mcg of intravenous fentanyl.
• The case histories demonstrate successful management of opioid challenges in patients receiving ER-NTX.
• This study provides the initial human evidence supporting ER-NTX's protective capacity against severe fentanyl toxicity.

Conclusions:

• Extended-release naltrexone is effective in blocking the life-threatening respiratory depression induced by high doses of fentanyl.
• ER-NTX represents a promising therapeutic option for mitigating overdose risk in individuals with opioid use disorder.
• Further research is warranted to establish optimal dosing and clinical protocols for ER-NTX in opioid overdose prevention.