Lomotil toxicity

Background

• Mixture of diphenoxylate / atropine used to treat diarrhea
• Children are especially sensitive to toxicity (death reported after ingestion of <5 tablets)

Mechanism of toxicity

• Diphenoxylate
  • opioid analog of meperidine, which has opioid-like toxicity in overdose
• Atropine
  • anticholinergic effects
• Toxic dose is variable

Clinical Features

• Atropine effects
  • Lethargy, agitation, flushing, dry mucous membranes, mydriasis, ileus, tachycardia
• Opioid effects
  • Miosis, coma, respiratory depression, respiratory arrest

Differential Diagnosis

Sedative/hypnotic toxicity

• Toxic alcohols
  • Ethanol
  • Ethylene glycol
  • Methanol
  • Isopropyl alcohol
• Benzodiazepines
  • Flunitrazepam (Rohypnol)
• Gamma hydroxybutyrate (GHB)
• Barbiturates
• Opioids
  • Lomotil toxicity
• Chloral hydrate
• Absinthe

Anticholinergic toxicity

• Medications
  • Atropine
    • Lomotil toxicity
  • Antihistamines
  • Antidepressants
    • Tricyclic antidepressant (TCA) toxicity
    • SSRIs
  • Antipsychotics
  • Muscle relaxants
  • Anti-Parkinsonians
• Plants
  • Jimson weed (Devil's trumpet)
  • Amanita mushroom

Evaluation

• Diagnosis is based on history and signs of toxicity

Management

• Maintain airway and support ventilation, if needed
• Naloxone 1-2mg IV for apnea, coma, or lethargy (may require repeat dosing)
• Activated charcoal should be given promptly if available
• No evidence for utility of physostigmine

Disposition

• Pediatric patients should be observed in the ICU for 24 hours given risk of sudden respiratory arrest

See Also

• Opioid toxicity

References

• Olson, K. Poisoning and Drug Overdose Clinical Manual. 2004

Authors

Ben Isakson, Ross Donaldson, Michael O'Brien, MD