Large and small airway responses to procaterol hydrochloride administered through different extension devices in asthmatic patients

J Aerosol Med. 1999 Fall;12(3):177-85. doi: 10.1089/jam.1999.12.177.


The effects of spacer devices on the magnitude and velocity of large and small airway bronchodilator responses in asthmatic patients who can correctly operate a metered dose inhaler (MDI) remain unclear. According to a double-blinded, randomized, crossover protocol, 14 asthmatic patients were studied on seven separate occasions. On each occasion, patients inhaled doubling methacholine concentrations until forced expiratory volume in 1 second (FEV1) had fallen by 20% of baseline. Changes in forced expiratory flow between 25% and 75% of vital capacity (FEF25-75) were also evaluated. Subsequently, patients were administered 20 or 50 micrograms of procaterol from an MDI either alone or in conjunction with a small- or large-volume spacer device. Changes in FEV1 and FEF25-75 corrected for baseline forced vital capacity (isoFEF25-75) were assessed at 3-minute intervals for 15 minutes and at 30 minutes. Spontaneous recovery was similarly evaluated. The time required to attain significant increases in both FEV1 and isoFEF25-75 was calculated in bronchodilator trials. With 20 micrograms of procaterol, both spacers allowed larger and faster FEV1 increases than the MDI alone (P < 0.01); with 50 micrograms, the velocity and magnitude of FEV1 increases were further enhanced in trials with the MDI alone. The lower procaterol dose via the large-volume spacer determined larger and faster isoFEF25-75 increases than the higher dose via both the small-volume spacer and the MDI alone (P < 0.01). Spacers enhance bronchodilation even in patients using MDIs optimally. Compared with both the small-volume device and the MDI alone, the large-volume spacer allows faster and larger small airway dilation with less than half of the procaterol dose.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Inhalation
  • Adolescent
  • Adult
  • Analysis of Variance
  • Asthma / diagnosis
  • Asthma / drug therapy*
  • Bronchi / drug effects*
  • Bronchodilator Agents / administration & dosage*
  • Child
  • Cross-Over Studies
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Equipment Design
  • Female
  • Humans
  • Male
  • Nebulizers and Vaporizers*
  • Procaterol / administration & dosage*
  • Regression Analysis
  • Respiratory Function Tests
  • Treatment Outcome


  • Bronchodilator Agents
  • Procaterol