What is the dosage of racemic epinephrine for nebulization in bronchospasm?

Racemic Epinephrine Nebulization Dosage for Bronchospasm

For bronchospasm in adults and children ≥4 years, administer 0.5 mL of 2.25% racemic epinephrine solution (approximately 11.25 mg) via nebulizer, which can be repeated every 3 hours as needed, not exceeding 12 inhalations in 24 hours. 1

Standard Dosing Protocol

Adults and Children ≥4 Years

• Dose: 0.5 mL of 2.25% racemic epinephrine solution (11.25 mg racemic epinephrine) 1
• Frequency: 1-3 inhalations every 3 hours as needed 1
• Maximum: Not more than 12 inhalations in 24 hours 1
• Supervision: Children should be supervised by an adult during use 1

Children <4 Years

• Consult a physician before use 1

Alternative Dosing from Research

• Higher doses studied: 4.5-9 mg racemic epinephrine via IPPV showed dose-dependent bronchodilation, with 9 mg producing 44% improvement in peak expiratory flow rate at 5 minutes 2
• Standard clinical dose: Many institutions use 0.5 mL of racemic epinephrine as a standard dose for all patients 3

Clinical Context and Limitations

Efficacy Considerations

Racemic epinephrine provides significantly less bronchoprotection than albuterol and should not be considered first-line therapy for acute bronchospasm. 4 In methacholine challenge studies, 10 mg racemic epinephrine (approximate nonprescription dose) produced a geometric mean PC20 of 10.2 mg/mL compared to 44 mg/mL with 1.25 mg albuterol (P=0.001), indicating substantially inferior bronchodilator efficacy 4.

Preferred Bronchodilator Therapy

• First-line for acute asthma: Nebulized β-agonists (salbutamol 5 mg or terbutaline 10 mg) 3
• Severe cases: Consider adding ipratropium bromide 500 μg to β-agonist therapy 3
• Frequency: Repeat every 4-6 hours for 24-48 hours or until clinical improvement 3
• Refractory bronchospasm: Nebulized albuterol 2.5-5 mg in 3 mL saline, repeated as necessary 3

When Racemic Epinephrine May Be Considered

• Primary indication: Laryngotracheobronchitis (croup) at 0.5 mL/kg (maximum 5 mL) of 2.25% solution 3
• Alternative for croup: If racemic epinephrine unavailable, L-epinephrine 1:1000 can be substituted at 0.5 mL/kg up to 5 mL 3
• Bronchospasm in specific contexts: May be used when standard β-agonists are unavailable, though this is suboptimal 1, 4

Administration Technique

Nebulizer Setup

• Gas flow rate: 6-8 L/min to nebulize 50% of particles to 2-5 μm diameter for optimal small airway deposition 5
• Volume in chamber: 2.0-4.5 mL 5
• Patient position: Sit upright during nebulization for optimal delivery 5

Post-Treatment Care

• Rinse mouth after nebulization to prevent oral candidiasis (particularly relevant for corticosteroid nebulization, but good practice for all nebulized medications) 5

Important Caveats

Beta-Blocker Interaction

Patients on beta-blockers may have reduced response to racemic epinephrine. 6 In such cases, consider:

• Inhaled metaproterenol or other β2-selective agonists may be more effective 6
• Glucagon 1-2 mg IV may be necessary as adjunctive therapy 3

Safety Profile

• Normal subjects and patients with airway obstruction showed no clinically significant changes in pulse rate or blood pressure with doses up to 9 mg 2
• Mild side effects were slightly more frequent with higher doses (9 mg vs 4.5 mg) 2

Cost and Practical Considerations

Racemic epinephrine is now marketed as a nonprescription replacement for epinephrine MDI (Primatene), but its inferior efficacy compared to albuterol makes it a suboptimal choice for treating acute bronchospasm. 4 Standard β-agonist therapy remains the evidence-based first-line treatment 3.