CD

Medetomidine

search

Medetomidine, Medetomidine Toxicity, Medetomidine Withdrawal

  • See Also
  1. Opioid Overdose
  2. Unknown Ingestion
  • Background
  1. Adulterant found in street Fentanyl used in Opioid Use Disorder
  2. May accompany other Fentanyl adulterants (e.g. Xylazine)
  • Mechanism
  1. Alpha 2 Adrenergic Agonist
    1. Used in veterinary medicine as a Sedative and Analgesic
    2. Medetomidine is more potent that Xylazine at a2 receptors by a factor of 10x to 100x
    3. Medetomidine acts at presynaptic alpha-2 receptors
      1. Decreases Norepinephrine release
      2. Decreases sympathetic outflow
      3. Results in sedation, Bradycardia, Hypotension
    4. Medetomidine Withdrawal
      1. Dependence may develop with chronic use
      2. Severe sympathetic activation may occur with abrupt Medetomidine discontinuation
  2. Medetomidine is a racemic mix
    1. Active Dexmedetomidine
    2. Inactive Levomedetomidine
  1. Respiratory depression
    1. Typically reverses with Naloxone
  2. Hemodynamic changes
    1. Bradycardia
    2. Hypotension (may be initially hypertensive)
    3. Hypothermia
    4. Reduced sympathetic tone
  3. Sedation to coma, slurred speech
    1. Persists despite Naloxone
  4. Miscellaneous
    1. Miosis
  • Findings
  • Medetomidine Withdrawal
  1. Associated with chronic alpha 2 Agonist exposure
  2. Abrupt discontinuation of alpha 2 Agonist results in a sympathetic surge
    1. Occurs 6 to 24 hours after last exposure (peaks at 24 to 72 hours)
    2. Severe cases may last 1-2 weeks (days in mild cases)
  3. Hemodynamic changes
    1. Severe Hypertension
    2. Sinus Tachycardia
    3. Dysrhythmias
    4. Diaphoresis
  4. Neurologic changes
    1. Tremor
    2. Agitation
    3. Encephalopathy (e.g. Delirium)
  5. Gastrointestinal
    1. Nausea
    2. Vomiting
  • Management
  • Medetomidine Withdrawal
  1. ABC Management
  2. Supportive Care
    1. Intravenous Fluids
    2. Antiemetics
    3. Benzodiazepines
    4. Antipsychotics
  3. Initiate alpha 2 Agonist
    1. Clonidine (mild to moderate cases)
    2. Dexmedetomidine (severe cases)
  4. Disposition
    1. Consider Clonidine patch for 1 week or oral Clonidine at the time of discharge
  • References
  1. Swadron and Nordt (2026) Medetomidine Toxicity and Withdrawal, EM:Rap, 3/16/2026
  2. Lynch (2026) Ann Emerg Med +PMID: 41575403 [PubMed]