Aerosol profile extracted from spacers as a determinant of actual dose

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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 mug salbutamol pMD1 (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 [Aerochamber Plus: 21.4 +/- 3.2 (SD) mug; Volumatic: 43.8 +/- 9.1 (SD) [mug].

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.
Original languageEnglish
Pages (from-to)2213-2218
Number of pages6
JournalPharmaceutical Research
Issue number12
Publication statusPublished - Dec 2004


  • aerosol
  • dose
  • metered dose inhalers
  • spacers

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