Background: Albuterol is the most commonly used β agonist to treat reversible lower airway obstruction. Albuterol contains a racemic mixture of two enantiomers. Levalbuterol contains the single R form enantiomer. Levalbuterol is frequently prescribed to limit cardiovascular toxicity.
Objective: We examined changes in oxygen consumption (V'O2) and heart rate (HR) following administration of albuterol and levalbuterol.
Methods: This is a prospective, randomized, single-blinded, controlled study of healthy adult volunteers. Subjects separately received albuterol (5 mg) and levalbuterol (2.5 mg) aerosolized over 15 min. V'O2 and vital signs were measured before the medications and 5, 10, 20, 40, and 60 min after.
Results: We enrolled 24 volunteers with a median age of 32 years. Compared to baseline, there was a significant maximum increase in V'O2 following administration of both albuterol (median 17% (1, 3 IQR 9, 43%) p < 0.001) and levalbuterol (median 23% (1, 3 IQR 10, 32%) p < 0.001). There was no significant difference between the maximum increase in V'O2 following administration of albuterol compared to levalbuterol (p = 0.57). Compared to baseline, there was a significant maximal increase in HR with both albuterol (median 30% (1, 3 IQR 19, 43%) p < 0.001) and levalbuterol (median 23% (1, 3 IQR 19, 31%) p < 0.001). There was a statistically significant greater increase in maximal HR following administration of albuterol as compared to levalbuterol (p = 0.009).
Conclusion: Albuterol and levalbuterol both cause a significant increase in V'O2 and HR. There was no significant difference between albuterol and levalbuterol regarding the maximum increase in V'O2. There was a statistically significant but likely clinically insignificant difference in maximum increase in HR in patients with adequate oxygen delivery when comparing albuterol to levalbuterol.
Keywords: Adrenergic β2 agonists; Albuterol; Levalbuterol; Oxygen consumption.