What are the intramuscular (IM) and intravenous (IV) doses of atropine for pediatric patients?

Atropine IM and IV Dosing in Pediatric Patients

For IV/IO administration, the standard pediatric dose of atropine is 0.02 mg/kg with a minimum single dose of 0.1 mg and maximum single dose of 0.5 mg for children (1.0 mg for adolescents), while for IM administration, the same weight-based dosing applies (0.01-0.03 mg/kg per FDA labeling), though IM use is primarily reserved for specific scenarios like organophosphate poisoning or when IV access is unavailable. 1, 2

Standard IV/IO Dosing by Clinical Indication

Symptomatic Bradycardia

• Initial dose: 0.02 mg/kg IV/IO 1, 3
• Minimum single dose: 0.1 mg for children (this minimum was removed for neonates in 2015 guidelines) 1, 3
• Maximum single dose: 0.5 mg for children, 1.0 mg for adolescents 1, 3
• Repeat dosing: Every 5 minutes as needed 1, 3
• Maximum total dose: 1 mg for children, 2 mg for adolescents 1, 3

Critical caveat: Oxygenation and ventilation are the essential first interventions before atropine, as hypoxia-induced bradycardia typically responds to these alone. 1, 3

Rapid Sequence Intubation (RSI) Premedication

• Dose: 0.01-0.02 mg/kg IV/IO, administered before sedative/anesthetic and paralytic agents 1, 3
• Important note: Do not routinely use atropine for RSI premedication in all pediatric patients, as it may be unnecessary for many patients and does not prevent bradycardia in all cases. 1, 4

Organophosphate/Nerve Agent Poisoning

• Initial dose: 0.02-0.05 mg/kg IV 1, 5
• Maximum single dose: 2-3 mg 1, 5
• Repeat dosing: As needed for clinical effect based on muscarinic symptoms (excessive secretions, bronchospasm, bradycardia, miosis) 1, 5
• Critical consideration: Cumulative doses may need to be substantially higher—adult patients may require 10-20 mg in the first 2-3 hours, and up to 50 mg in 24 hours before full muscarinic antagonism appears. 1
• Essential adjunct: Must be combined with oximes (pralidoxime) to address nicotinic receptor dysfunction and respiratory muscle paralysis, as atropine alone has minimal effect on these symptoms. 1, 5

IM Administration

When to Use IM Route

• Primary indication: When IV/IO access is unavailable or delayed 1
• Specific scenario: Organophosphate poisoning in mass casualty situations where IM administration is faster and easier than establishing IV access 6, 7

IM Dosing

• Standard dose: 0.01-0.03 mg/kg IM (per FDA labeling) 2
• For nerve agent exposure in children >1 year: Full dose from Mark 1 autoinjector (2 mg atropine) when accurate weight-based dosing is impossible 7
• For infants <1 year: 0.5 mg from Atropen autoinjector 7

IM Site Considerations

Submental glossal injection provides the fastest onset (3.0 ± 1.1 minutes), significantly faster than deltoid (4.4 ± 1.1 minutes) or vastus lateralis (6.4 ± 2.4 minutes) in anesthetized children. 8 However, this route is primarily used in the operating room setting during halothane-induced bradycardia, not in emergency situations. 8

Alternative Route: Endotracheal Administration

When IV/IO access is unavailable:

• Neonates: 0.01-0.03 mg/kg ET 1, 3
• Children and adolescents: 0.03-0.06 mg/kg ET 1, 3
• Administration technique: Follow with or dilute in saline flush (1-5 mL) based on patient size 1, 3

Critical Safety Considerations

Dosing Errors

• Major pitfall: Atropine sulfate comes in different concentrations (0.4 mg/mL and 1 mg/mL)—calculate dosage carefully to avoid 10-fold errors, which are common with pediatric dosing. 1

Administration Technique

• For cardiac arrest: Administer by slow IV push to avoid paradoxical bradycardia 1, 3
• Monitoring: Observe for reversal of bradycardia within 3 minutes (peak action time) 1

Contraindications and Cautions

• Do not use for type II second-degree AV block or third-degree AV block with wide-complex escape rhythm—atropine is ineffective and potentially harmful in these conditions 1
• Coronary artery disease: Limit total dose to 0.03-0.04 mg/kg to avoid tachycardia-induced ischemia 2, 1
• Organophosphate poisoning: Do not withhold adequate doses due to fear of overdose—inadequate dosing can be fatal, and atropine overdose is generally well tolerated in young children 1, 7

Tolerance of Higher Doses

Data demonstrate that atropine overdose is generally well tolerated in young children, and symptomatic children with nerve agent poisoning will likely need both supraphysiologic doses and frequent re-dosing. 7