Pulmonology Book

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Dextromethorphan Toxicity

Aka: Dextromethorphan Toxicity, Dextromethorphan Abuse, Dextromethorphan Overdose
  1. See Also
    1. Dextromethorphan
  2. Background
    1. Dextromethorphan Abuse is increasing in United States (especially among teens)
    2. Common Dextromethorphan sources used for abuse
      1. Coricidin Cough and Cold ("skittles", Triple C with DM and Chlorpheniramine)
        1. Many other Coricidin products contain Acetaminophen (see precautions below)
      2. Extract Dextromethorphan from OTC preparations (Crystal-Dex)
      3. Pure Dextromethorphan as a "research chemical" via the internet
  3. Mechanism
    1. Dextromethorphan has NMDA activity and serotonergic activity
  4. Signs
    1. General
      1. Altered Level of Consciousness
      2. Does not typically cause respiratory depression
    2. Dose-Dependent Effects
      1. Typical Antitussive dose (20-30 mg every 4-6 hours)
        1. Cough Suppressant
        2. Adverse effects include Nausea, Vomiting, drowsiness, Sedation and agitation
      2. Low dose (100-200 mg)
        1. Mild euphoria
        2. Increased energy
        3. Ataxia on ambulation ("robo walk")
      3. High dose (>200-400 mg Dextromethorphan)
        1. Euphoria
        2. Auditory Hallucinations and Visual Hallucinations
      4. Higher dose (400 to 1000 mg Dextromethorphan)
        1. Partial dissociation
      5. Very high dose (1000 mg or 500 ml of 20 mg/10 ml Dextromethorphan)
        1. Complete dissociation
    3. Combination product abuse
      1. Acetaminophen Toxicity risk (see below)
      2. Anticholinergic Toxicity
        1. Combination products containing Diphenhydramine or Chlorpheniramine
  5. Labs
    1. Hyperchloremia and normal Anion Gap (or negative Anion Gap - a cation gap)
      1. Limited to Dextromethorphan preparations containing hydrobromide salt
      2. Results in falsely elevated Serum Chloride (due to bromide being read by analyzers as chloride)
    2. Acetaminophen Level
      1. Elevated if combination product was abused
    3. Salicylate Level
    4. Liver Function Tests and INR
      1. Evaluate for chronic excessive Acetaminophen ingestions and secondary hepatotoxicity
  6. Precautions
    1. Acetaminophen Toxicity risk
      1. Many Dextromethorphan products also contain Acetaminophen
    2. Anticholinergic Toxicity risk
      1. Associated with combination agent Overdose containing Diphenhydramine
      2. "Cheese" (Heroin with Dextromethorphan and Diphenhydramine)
    3. Serotonin Syndrome risk
      1. See below
      2. Avoid combining with other serotonergic agents (e.g. Zofran - use Haloperidol as alternative Antiemetic)
  7. Management
    1. Supportive care
    2. Naloxone is unlikely to have much effect unless there is respiratory depression
    3. Agitation management
      1. Benzodiazepines
    4. Serotonin Syndrome management
      1. See Serotonin Syndrome
  8. Course
    1. Short acting agents: 6 hours
    2. Long acting agents (Delsym): 12 hours
  9. Complications
    1. Serotonin Syndrome (when combined with other serotonergic agents)
      1. Dextromethorphan is a non-Selective Serotonin Reuptake Inhibitor
      2. At very high dose, Dextromethorphan alone could cause Serotonin Syndrome
      3. Observe for Clonus as a hallmark finding in Serotonin Syndrome
  10. References
    1. Fontes (2014) Crit Dec Emerg Med 28(1): 14-24
    2. Nordt and Swadron in Majoewsky (2017) EM: RAP 17(9): 15
    3. Nordt and Swadron in Majoewsky (2012) EM: RAP 12(5): 3

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