II. Indications
- Opioid Toxicity requiring frequent Naloxone dosing
- Alcohol Abuse
III. Background
- First approved for Opioid Overdose in U.S. as of 1995, but was discontinued by manufacturer in U.S. in 2006
- Has been used in Europe for Alcohol Abuse (similar to Naltrexone)
IV. Mechanism
- Long acting opioid Antagonist similar to Naltrexone
- Nalmafene is a 6-methylene analogue of Naltrexone
- Mu and lambda Opioid receptor Antagonist
- Partial kappa Opioid receptor Agonist
V. Precautions
- Do not use as a first line agent for Opioid Overdose
- Risk of severe and prolonged Opioid Withdrawal
VI. Pharmacokinetics
- Long acting opioid Antagonist
- Duration
- IV: 4-8 hours
- Intranasal: 6 hours
- Contrast with 2 hours for intranasal Naloxone
- Plasma Half-Life up to 11 hours (contrast with 2 hours for Naloxone)
- Mildly decreased clearance in elderly or liver or Kidney disease
-
Bioavailability
- Intranasal: 80%
- IM or SQ: 100%
- Onset
- IV 2 to 5 minutes
- IM: 5 to 15 minutes (peak effect 2 to 3 hours)
- SQ: 5 to 15 minutes (peak effect 1.5 hours)
- Intranasal (Opvee): 2.5 to 5 minutes (peak effect 15 minutes, up to 3 hours)
VII. Dosing: IV
-
Opioid Overdose
- Initial: 0.5 mg per 70 kg person IV
- Later: 1 mg per 70 kg IV prn 5 min after initial dose
- Opioid dependent: 0.1 mg per 70 kg test dose
- Post-operative Opioid reversal
- Dose: 0.25 ug/kg IV q2-5 minutes
- Maximum: 1 ug/kg total dose
VIII. Dosing: Intranasal (Opvee)
-
Opioid Overdose
- Give 2.7 mg/0.1 ml (one actuation)
IX. Adverse Effects
- Serious
- Severe and prolonged Opioid Withdrawal
- Common (general)
- Common (nasal Inhaler)
- Nasal discomfort, nasal congestion, Rhinorrhea
- Throat irritation
X. Resources
- Nalmefene Injectable (DailyMed)
- Nalmefene Intranasal (DailyMed)
- Nalmefene (Wikipedia)
XI. References
- LoVecchio (2023) Crit Dec Emerg Med 37(9): 32