Atropine
AtroPen
Tertiary amine muscarinic antagonist
Competitive antagonist at muscarinic ACh receptors. Tertiary amine → CROSSES blood-brain barrier (in contrast to glycopyrrolate) → central anticholinergic effects possible. Faster onset than glycopyrrolate; useful for emergent bradycardia.
Indications
- •Symptomatic bradycardia (sinus, AV block — first-line in ACLS)
- •Pediatric bradycardia (especially with succinylcholine in <1 yr)
- •Pretreatment for second succinylcholine dose
- •Organophosphate poisoning (large doses)
- •Antisialagogue (less preferred than glycopyrrolate due to CNS effects)
- •Asystole (historical — removed from ACLS 2010 update)
Dosing
| Context | Adult | Pediatric |
|---|---|---|
| Adult bradycardia | 0.5 mg IV q3–5 min, max 3 mg | — |
| Pediatric bradycardia | 0.02 mg/kg IV (min 0.1 mg, max 0.5 mg single dose) | |
| Pre-succinylcholine in infants | 0.02 mg/kg IV at induction | |
| Organophosphate poisoning | 1–2 mg IV bolus, double q5 min until secretions dry; can require huge doses (>100 mg) | — |
| Reversal pairing (less common) | 0.015 mg/kg IV with neostigmine | 0.02 mg/kg IV |
Pharmacokinetics
Onset 30–60 sec IV (faster than glyco). Duration 30–60 min. Hepatic + plasma esterase metabolism + renal excretion.
Hemodynamic effects
↑HR (more pronounced than glyco). Paradoxical bradycardia at LOW doses (<0.5 mg adult) due to central vagal stimulation — avoid this dosing in adults.
Respiratory effects
Mild bronchodilation, reduces secretions.
Side effects
- !Tachycardia/AF (problematic in CAD)
- !Central anticholinergic syndrome: confusion, agitation, delirium, hyperthermia (especially in elderly + pediatric — physostigmine treats)
- !Mydriasis + cycloplegia (avoid in narrow-angle glaucoma)
- !Urinary retention
- !Hyperthermia (decreased sweating)
Contraindications
- ×Narrow-angle glaucoma
- ×Bladder outlet obstruction
- ×Severe tachyarrhythmia
Clinical pearls
- ★Pediatric < 1 yr + succinylcholine: GIVE atropine 0.02 mg/kg routinely — prevents profound bradycardia/asystole.
- ★Use for EMERGENT bradycardia where glycopyrrolate's slower onset is too slow.
- ★AVOID dose <0.5 mg in adults — paradoxical bradycardia.
- ★Beware central anticholinergic syndrome in elderly: confusion + delirium + hyperthermia. Physostigmine 1–2 mg IV reverses (crosses BBB unlike neostigmine).
- ★ACLS 2010+: removed from asystole/PEA algorithm. Still first-line for symptomatic bradycardia.
Education only — confirm against current package inserts and institutional protocols. Doses assume normal organ function unless otherwise noted.