Management of Atropine Toxicity
For suspected atropine toxicity, administer physostigmine 1-4 mg IV slowly (0.5-1 mg in children) as the primary antidote, with benzodiazepines (diazepam or short-acting barbiturates) for marked excitement and convulsions, while providing supportive care including cooling measures and artificial respiration with oxygen as needed 1.
Recognition of Atropine Toxicity
Atropine toxicity presents with a classic anticholinergic syndrome that progresses through distinct stages:
Early/Moderate toxicity:
- Palpitations and tachycardia
- Dilated pupils (mydriasis)
- Dry, hot, flushed skin
- Difficulty swallowing
- Thirst
- Dizziness, restlessness, tremor, fatigue, and ataxia 1
Severe toxicity:
- Marked excitement and hallucinations
- Delirium progressing to coma
- Late-stage circulatory collapse and respiratory depression
- Death from respiratory failure following paralysis and coma 1
Critical dosing threshold: In pediatric populations, as little as 10 mg may be fatal, though the fatal adult dose is not precisely known 1.
Primary Antidote: Physostigmine
Physostigmine is the definitive antidote that rapidly reverses atropine-induced delirium and coma by inhibiting acetylcholinesterase 1, 2.
Dosing protocol:
- Adults: 1-4 mg IV administered slowly
- Pediatric patients: 0.5-1 mg IV administered slowly 1
Important caveats about physostigmine:
- It is rapidly metabolized, with effects lasting only 1-2 hours
- Patients may relapse into coma after initial response
- Repeated doses are frequently required 1
- Much higher cumulative doses may be necessary in massive ingestions—one case report documented successful use of 14 mg total to avoid intubation in a patient who ingested 150 mg of atropine 2
Adjunctive Management
For agitation and seizures:
- Administer diazepam or short-acting barbiturates as needed to control marked excitement and convulsions 1, 3
- Avoid large sedative doses as central depressant effects may coincide with the late-stage depression of atropine poisoning 1
- Do not use central stimulants 1
Supportive care measures:
- Cooling interventions: Ice bags and alcohol sponges to reduce hyperthermia, especially critical in pediatric patients 1
- Respiratory support: Artificial respiration with oxygen may be necessary for respiratory depression 1
- Monitoring: Continuous cardiac and hemodynamic monitoring given the risk of tachycardia and late circulatory collapse
What NOT to Do
- Dialysis is ineffective—atropine is not removed by dialysis 1
- Avoid central stimulants entirely 1
- Do not give excessive sedation that could worsen late-stage respiratory depression 1
Clinical Pitfall
The most common error is failing to anticipate the need for repeated physostigmine doses. Because physostigmine has a short duration of action (1-2 hours) while atropine toxicity may persist much longer, clinicians must remain vigilant for recurrence of symptoms and be prepared to re-dose physostigmine multiple times 1. One case series demonstrated that patients can safely receive much higher cumulative doses than typically described (up to 14 mg) when clinically indicated 2.