Particle Size Alters Impact Of Inhaled Asthma Medication
Smaller particles penetrate more deeply; larger are more effective bronchodilators
WEDNESDAY, Dec. 28 (HealthDay News) -- While smaller inhaled albuterol particles penetrate deeper into the lungs of asthma patients, larger particles are better at targeting the proximal airway and are more effective bronchodilators, according to a study in the American Journal of Respiratory and Critical Care Medicine.
Omar S. Usmani, M.D., of the National Heart and Lung Institute at Imperial College London, U.K., and colleagues used technetium-99m-labeled albuterol to measure both drug delivery and efficacy of aerosols containing different-sized particles. Twelve subjects with mild or moderate asthma were randomized to an equivalent dose of albuterol aerosol containing either 1.5, 3 or 6 micron diameter particles.
The investigators found that smaller particles had greater lung deposition (1.5 micron, 56%; 3 micron, 50%; and 6 micron, 46%) and penetrated deeper into the distal airways (0.79, 0.60, and 0.36, respective penetration index). However, the larger particles were more effective at bronchodilation as the 6 micron particles increased FEV1 by 551 mL compared with only 347 mL for the 1.5 micron particles.
"Altering intrapulmonary deposition through aerosol particle size can appreciably enhance inhaled drug therapy and may have implications for developing future inhaled treatments," the authors conclude.