Known brand names include Atropen and Isopto Atropine.
An injectable anticholinergic that blocks acetylcholine at muscarinic receptors. It speeds up a dangerously slow heart rate, dries secretions before and during surgery, and is the antidote for organophosphate insecticide, carbamate, and certain mushroom poisonings.
Labeled use. Symptomatic bradycardia; not reliable for wide-complex second- or third-degree AV block.
Labeled use. Antidote for organophosphorus, carbamate, or muscarinic mushroom poisoning.
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First-line drug for symptomatic sinus bradycardia or AV nodal block; if it fails, move to transcutaneous pacing, dopamine, or epinephrine. It is not effective for infranodal (wide-complex) blocks or a transplanted heart. In organophosphate poisoning, atropine treats muscarinic effects and is paired with pralidoxime to reactivate cholinesterase.
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A competitive (surmountable) muscarinic antagonist. It blocks acetylcholine at exocrine glands and smooth and cardiac muscle, which abolishes reflex vagal slowing of the heart and dries secretions. Small doses may briefly slow the heart before tachycardia develops. In cholinergic poisoning it reverses bronchorrhea and bronchospasm. The plasma half-life is about 2 to 4 hours, longer in children under 2 and adults over 65.
The label does not describe a narrow therapeutic index or direct dosing by measured blood levels of the drug.
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Doses come from the FDA label. Study tool, not for clinical decisions.
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No labeled dose change. Between 13% and 50% is excreted unchanged in urine.
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No labeled dose change. Much of the drug is broken down by enzymatic hydrolysis, mainly in the liver.
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Physostigmine by slow IV injection (1 to 4 mg in adults, 0.5 to 1 mg in children) rapidly reverses delirium and coma from atropine overdose; it is short-acting, so doses may need repeating. Control marked excitement or seizures with a short-acting barbiturate or diazepam, support breathing, and cool the patient. Dialysis does not remove atropine.
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Data are limited, and observational studies have not shown a clear rise in birth defects. Severe muscarinic emergencies such as organophosphate poisoning or symptomatic bradycardia can be fatal, so life-sustaining treatment should not be withheld in pregnancy. Atropine crosses the placenta.
Traces appear in milk after oral use; no data after IV use. To minimize infant exposure, a mother may pump and discard milk for 24 hours after a dose.
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Weight-based dosing, for example 0.02 mg/kg for symptomatic bradycardia or as an antisialagogue. The half-life more than doubles under age 2, small children are prone to atropine fever, and 10 mg or less may be fatal in children. Benzyl alcohol in the vial has been linked to gasping syndrome in neonates.