fentanyl + naltrexone

Fentanyl + naltrexone is a theoretical or investigational drug combination that pairs fentanyl, a potent synthetic opioid agonist, with naltrexone, an opioid receptor antagonist. Fentanyl acts primarily as a μ-opioid receptor agonist to produce analgesia and euphoria but carries high risks of respiratory depression and overdose. Naltrexone is a competitive antagonist at μ-, κ-, and δ-opioid receptors in the central nervous system, with the highest affinity for the μ-receptor. It blocks the effects of opioids like fentanyl by preventing their binding to these receptors[1][5]. This combination is not approved as a marketed pharmaceutical product; however, similar combinations (such as oxycodone/naltrexone) have been developed to deter abuse by blocking opioid effects if tampered with[8]. The primary indication for such combinations would be pain management with built-in abuse deterrence or research into overdose prevention.