Atropine

	First drug for symptomatic bradycardia.
	Second drug (after epinephrine or vasopressin) for asystole or bradycardic pulseless electrical activity.
	May be beneficial in presence of AV block at nodal level or ventricular asystole; Will not be effective when infranodal (Mobitz type II) block is suspected.
	Prevention/treatment of vagally mediated bradycardia (pediatrics).
	Prevention of succinylcholine-induced bradycardia (pediatrics).
	Prophylaxis for strabismus surgery: oculocardiac reflex (pediatrics).
	Antisialogogue.
	Reversal of neuromuscular blockade (blocks muscarinic effect of  anticholinesterases).
	Adjunctive therapy in the treatment of bronchospasm.
	Organophosphate poisoning (seek specialist advice).

CLASS: Anticholinergic agent (tertiary amine).

MODE OF ACTION: Competitive (muscarinic) blockade of acetylcholine.

ONSET: IV: 45-60 s; intratracheal 10-20 s; inhalation 3-5 min.

DURATION: Variable, vagal blockade 1-2 h, antisialogogue effect for 4 h.

CLEARANCE: Hepatic metabolism, renal elimination

ADULT DOSE:

	Asystole or pulseless electrical activity (PEA): 1 mg IV push, repeat every 3-5 min (if asystole persists) to maximum 0.03-0.04 mg/kg.
	Bradycardia: 0.5-1 mg IV every 3-5 min, not to exceed total dose 0.04 mg/kg.
	Endotracheal administration: 2-3 mg diluted in NaCl 0.9% 10 mL.
	Reversal of neuromuscular blockade: 10 µg/kg IV administered with or before anticholinesterase.
	Bronchial dilatation: inhalation of 0.025 mg/kg/dose in NaCl 0.9% 2.5 mL every 4-6 h.

PEDIATRIC DOSE:

	Bradycardia: 0.02 mg/kg IV or intraosseous every 5 min
	Minimum single dose: 0.1 mg.
	Maximum child single dose: 0.5 mg.
	Maximum adolescent single dose: 1 mg.
	May double dose for second IV/IO dose.
	Endotracheal administration: 2-2.5 times IV dose, add 1-2 mL NS to total volume.
	0.01-0.02 mg/kg IV for prevention of reflex bradycardia during intubation or suction, or after the administration of  succinylcholine.
	Bronchospasm: inhalation of 0.05 mg/kg/dose (minimal dose 0.25 mg, maximal 1 mg), in NaCl 0.9% 2.5 mL every 6-8 h.

NEONATAL DOSE: 0.02 mg/kg IV; endotracheal 2-3 times the IV dose in NaCl 0.9% 1-2 mL. Adequate oxygenation/ventilation must precede treatment of bradycardia.

CAUTION:

	Low doses < 0.1 mg may cause paradoxical bradycardia secondary to central action.
	Sensitivity to sulphites.
	Presence of myocardial ischemia and hypoxia.
	Avoid in elderly when possible (see below).

CONTRAINDICATIONS:

	Avoid in hypothermic bradycardia, hyperpyrexia, pheochromocytoma.
	Not effective for infranodal AV block and new 3rd degree block with wide QRS (may cause paradoxical slowing; consider pacing or catecholamines).
	Narrow-angle glaucoma, obstructive uropathy, tachycardia, thyrotoxicosis.

INTERACTIONS:  Increased risk of anticholinergic effects with phenothiazines, haloperidol, amantadine, antiparkinsonian drugs, pethidine, tricyclic antidepressants, MAOIs, procainamide, quinidine, antihistamines.

ADVERSE REACTIONS:

	Severe paradoxical bradycardia.
	Anaphylaxis, decreased diaphoresis, hyperpyrexia.
	CNS signs: dizziness, hallucinations, restlessness, headaches, blurred vision, mydriasis, tremor, confusion, delirium, vomiting.
	Tachydysrhythmias.
	Dry mouth.

PREGNANCY: Category C. 

CENTRAL ANTICHOLINERGIC SYNDROME: May appear in elderly patients following atropine administration. Administer physostigmine (anticholinesterase), a tertiary amine that passes into the CNS, to counteract antimuscarinic activity. Adult dose: 0.5-2 mg slow IV to avoid peripheral cholinergic activity (acts within 5 min). Pediatric dose: 0.01-0.03 mg/kg/dose slow IV (maximum 0.5 mg/min).