Analgesic

Nalmefene

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Nalmefene, Revex, Opvee

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