Aerosol profile extracted from spacers as a determinant of actual dose

Pharm Res. 2004 Dec;21(12):2213-8. doi: 10.1007/s11095-004-7673-7.


Purpose: We propose a novel method to evaluate the efficacy of a pressurized metered dose inhaler (pMDI) in combination with a spacer, by not only considering the total dose extractable from the spacer but also the dependence of dose on the volume available for aerosol inhalation.

Methods: We studied volume-dependence of aerosol concentration during extraction from two commonly used plastic spacers (150 ml AerochamberPlus; 750 ml Volumatic) after a single puff of a 100 microg salbutamol pMDI (HFA-Ventolin), using laser photometric measurements.

Results: After a delay of is in each spacer, the aerosol peak dose for AerochamberPlus was 2-fold that for Volumatic (p < 0.001), with the peak appearing well within the first 0.5 L even for the largest spacer. The opposite dose relationship is reached when considering total cumulative dose, which was 2-fold higher for Volumatic than for AerochamberPlus (p < 0.001); >95% of total cumulative dose was extracted well within 3 L for the largest spacer. The 2-fold cumulative dose relationship was confirmed by chemical assay on an absolute filter [AerochamberPlus: 21.4+/-3.2 (SD) microg; Volumatic: 43.8+/-9.1 (SD) microg].

Conclusions: Actual aerosol dose available to patients during inhalation via spacers can only be done on the basis of a quantification of aerosol peak dose and cumulative dose as a function of extracted volume.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Inhalation
  • Aerosols / administration & dosage*
  • Albuterol / administration & dosage*
  • Metered Dose Inhalers / standards*


  • Aerosols
  • Albuterol