Change in Oxygen Consumption Following Inhalation of Albuterol in Comparison with Levalbuterol in Healthy Adult Volunteers

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.