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

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

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

References

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