From the FDA Drug Label
OVERDOSAGE Manifestations - May be any of those seen in atropine poisoning or antihistamine overdosage: CNS depression, preceded or followed by stimulation; confusion; nervousness; listlessness; intensification of mental symptoms or toxic psychosis in patients with mental illness being treated with neuroleptic drugs (e.g., phenothiazines); hallucinations (especially visual); dizziness; muscle weakness; ataxia; dry mouth; mydriasis; blurred vision; palpitations; tachycardia; elevated blood pressure; nausea; vomiting; dysuria; numbness of fingers; dysphagia; allergic reactions, e.g., skin rash; headache; hot, dry, flushed skin; delirium; coma; shock; convulsions; respiratory arrest; anhidrosis; hyperthermia; glaucoma; constipation. Treatment - Physostigmine salicylate, 1 to 2 mg, SC or IV, reportedly will reverse symptoms of anticholinergic intoxication. * A second injection may be given after 2 hours if required. Otherwise treatment is symptomatic and supportive Induce emesis or perform gastric lavage (contraindicated in precomatose convulsive, or psychotic states). Maintain respiration A short-acting barbiturate may be used for CNS excitement, but with caution to avoid subsequent depression; supportive care for depression (avoid convulsant stimulants such as picrotoxin, pentylenetetrazol, or bemegride); artificial respiration for severe respiratory depression; a local miotic for mydriasis and cycloplegia; ice bags or other cold applications and alcohol sponges for hyperpyrexia, a vasopressor and fluids for circulatory collapse. Darken room for photophobia.
The treatment for benztropine overdose includes:
- Physostigmine salicylate (1 to 2 mg, SC or IV) to reverse symptoms of anticholinergic intoxication, with a possible second injection after 2 hours if required 1
- Symptomatic and supportive treatment, such as:
- Inducing emesis or performing gastric lavage (if not contraindicated)
- Maintaining respiration
- Using a short-acting barbiturate for CNS excitement (with caution)
- Providing supportive care for depression
- Using artificial respiration for severe respiratory depression
- Applying a local miotic for mydriasis and cycloplegia
- Using ice bags or other cold applications and alcohol sponges for hyperpyrexia
- Administering a vasopressor and fluids for circulatory collapse
- Darkening the room for photophobia
From the Research
The treatment for benztropine overdose primarily involves supportive care and administration of physostigmine as an antidote, as supported by the most recent and highest quality study available 2. The initial management of benztropine overdose includes:
- Airway protection
- Vital sign monitoring
- Intravenous fluids Physostigmine, a cholinesterase inhibitor, can be administered at 1-2 mg IV slowly over 5 minutes for adults (0.02 mg/kg for children), with repeat doses as needed based on clinical response, as recommended in the literature 2. This medication works by increasing acetylcholine levels to counteract the anticholinergic effects of benztropine. Activated charcoal may be given if the ingestion was recent (within 1-2 hours). Benzodiazepines can be used to control agitation or seizures, with lorazepam 1-2 mg IV or diazepam 5-10 mg IV as common options. Temperature management is essential as hyperthermia is a serious complication. Avoid medications with anticholinergic properties as they can worsen symptoms. Cardiac monitoring is necessary due to potential arrhythmias, and bladder catheterization may be required for urinary retention. The patient should be monitored in a healthcare setting until anticholinergic symptoms resolve, which typically occurs within 24-48 hours for most cases, as indicated by the available evidence 2, 3.
The use of physostigmine in the treatment of anticholinergic toxicity, including benztropine overdose, has been supported by recent studies 2, which highlight its efficacy in both diagnosis and management of severe anticholinergic toxicity. Although other studies have reported on the toxicity and fatality associated with benztropine overdose 4, 3, the most recent and highest quality study available 2 provides the best guidance for treatment. Additionally, the importance of careful patient selection and consideration of potential contraindications when administering physostigmine or other antidotes is emphasized in the literature 5.
In terms of specific treatment protocols, the administration of physostigmine at a dose of 1-2 mg IV slowly over 5 minutes for adults (0.02 mg/kg for children) is recommended, with repeat doses as needed based on clinical response 2. The use of activated charcoal, benzodiazepines, and other supportive care measures should be tailored to the individual patient's needs and clinical presentation. Overall, the treatment of benztropine overdose requires a comprehensive and supportive approach, with careful consideration of the patient's clinical status and potential complications.