The importance of particle size in response to inhaled bronchodilators

The effect of 250 micrograms terbutaline sulphate of three different particle sizes from a metered dose inhaler was examined in ten non-asthmatic and ten asthmatic subjects. Particle size ranges were approximately less than five micrometers, five to ten micrometers and ten to fifteen micrometers. Responses to the less than five micrometers range were significantly greater than those to the larger sizes in both groups of subjects. In the asthmatic patients there was a suggestion that the difference between small and large particles was more marked for V50 than sGaw reflecting poorer penetration of large particles into smaller airways.