Dextromethorphan toxicity

Background

• Antitussive agent
• Acts on opioid and seratonin receptors
• At high doses has phencyclidine (PCP) and ketamine like effects on the NMDA receptor system
• High abuse in 12-25 year olds for euphoric and dissociative properties
  • "Skittles", "Robotripping"

Bright red pills resemble skittles

Clinical Features

• Diaphoresis, hyperthermia, tachycardia
• Visual field distortion and dilated pupils
• Excitement, euphoria, hallucinations, loss of time, feelings of dissociation, inappropriate laughing
• Less respiratory depression compared to other opioids (does not act on mu/delta receptors)
• Reactions with other medications
  • If anti-H1 in combination, Anticholinergic toxicity
  • If α-agonist in combination, hypertension and reflex bradycardia
  • If Acetaminophen in combination, hepatic toxicity
  • One of several medications that may precipitate Serotonin Syndrome

Toxicity is dose dependant

• Normal dose of nyquil (30 mL) has 30mg of dextromethorphan

Plateau	Dose	Symptoms
1	100 to 200mg	Mild stimulation, change in gravity perception
2	200 to 400mg	Euphoria and hallucinations
3	300 to 600mg	Dissociative and out of body sensation
4	>600mg	Complete dissociation and unresponsiveness, coma

Differential Diagnosis

Dissociative drugs

• Dextromethorphan
• Ketamine
• Nitrous oxide
• Phencyclidine (PCP)

• NMDA receptor antagonist

Hallucinogens

• LSD
• 25C-NBOMe
• Phencyclidine
• Mescaline (Peyote)
• Psilocybin/Mushroom Poisoning
• N,N-Dimethyltryptamine
• Ecstasy (MDMA)
• PCP
• Bath Salts
• Salvia toxicity
• Marijuana
• Absinthe

Evaluation

• Given altered mental status, key importance of witnesses and EMS recovery of medication bottles
• Acetaminophen level (combination cold medicine)
• Urine drug screen may be positive for PCP or opioids

Management

• Supportive care
  • IV hydration
  • Cooling
  • Benzodiazepines
• Naloxone is unlikely to have much effect unless there is respiratory depression

See Also

• Serotonin Syndrome
• Anticholinergic Toxicity

References

Authors

Daniel Eggeman, Ross Donaldson, Neil Young, Daniel Ostermayer