Racemic Epinephrine Concentration for Croup
Racemic epinephrine for croup is supplied as a 2.25% inhalation solution, with a dose of 0.05 mL/kg (maximum 0.5 mL) diluted in 2 mL of normal saline and administered by nebulizer. 1
Standard Concentration and Dosing
The commercially available racemic epinephrine concentration is 2.25%, which contains 11.25 mg of racepinephrine per 0.5 mL (equivalent to 13.5 mg of racepinephrine HCl). 2
The American Academy of Pediatrics recommends 0.05 mL/kg (maximum 0.5 mL) of the 2.25% solution diluted in 2 mL of normal saline for nebulization in children with croup. 1
Many institutions use a standard 0.5 mL dose of racemic epinephrine for all patients regardless of weight, which simplifies administration without compromising safety. 1
Alternative: L-Epinephrine Substitution
If racemic epinephrine is unavailable, L-epinephrine (1:1000 concentration) can be substituted at 0.5 mL/kg up to 5 mL administered by nebulizer. 1
L-epinephrine is equally effective as racemic epinephrine for croup treatment, with no difference in croup score reduction at 30 minutes and no additional adverse effects. 3
L-epinephrine offers practical advantages: it is more readily available worldwide, less expensive, and does not require special formulation. 3
Clinical Context and Efficacy
Nebulized epinephrine produces significant transient reduction in croup symptoms at 30 minutes post-treatment (SMD -0.94; 95% CI -1.37 to -0.51), though this effect diminishes by 2 hours. 4
The therapeutic effect is temporary, which is why observation for at least 2 hours after each dose is recommended before making disposition decisions. 1
Recent evidence suggests that admission should be considered after 3 total doses of racemic epinephrine rather than the traditional 2 doses, as 80% of admitted patients require no further airway interventions. 1
Dosing Considerations
Lower doses of L-epinephrine (0.1 mg/kg) are non-inferior to conventional doses (0.5 mg/kg) for moderate to severe croup, with equivalent croup score reduction at 30 minutes and no difference in cardiovascular effects. 5
The dose should always be combined with systemic corticosteroids (dexamethasone 0.6 mg/kg) as standard croup management. 5
Critical Safety Points
Do not confuse racemic epinephrine 2.25% solution with standard epinephrine 1:1000 or 1:10,000 concentrations used for other indications—these are entirely different formulations with different dosing. 1
Racemic epinephrine for croup is administered only by nebulization, never by intramuscular, subcutaneous, or intravenous routes. 1
Intermittent positive pressure breathing (IPPB) offers no advantage over simple nebulization for epinephrine delivery in croup. 4