Table 5– Advantages and disadvantages of pressurised metered-dose inhalers (pMDIs), pMDIs with spacers, breath actuated (BA)-pMDIs, nebulisers and dry powder inhalers (DPIs)
TypeAdvantagesDisadvantages
HFA-pMDIs (suspension and solution)Portable and compact.Coordination of actuation and inhalation needed.
Short treatment time.Most patients inhale too fast.
No contamination risk.Low lung deposition and high oropharyngeal deposition.
High reproducibility between doses.Important to prime before use if new or not used in some time.
Must be kept upright during inhalation.
With most devices, the number of doses remaining is difficult to determine. Only one β2-adrenergic agonist device has a dose counter (Ventolin®) and it is only available in the USA. Seretide® and Symbicort® (combination drug devices) have dose counters. Symbicort® is only available in the USA.
Few drugs available as breath-actuated pMDIs.
HFA-pMDIs (extra-fine particles)As above for pMDIs.Important to prime before use if new, or not used in some time.
Higher lung deposition and lower oropharyngeal deposition, compared with pMDIs that are used alone.
Good for inhaled corticosteroids. When using QVAR®, the corticosteroid dose can be half of that prescribed for patients using traditional corticosteroid pMDI products.Only two corticosteroid products available (QVAR® and Alvesco®). Only one combination product available (Foster®).
pMDI+spacersLess need for coordination of actuation and inhalation compared with a pMDI alone.More expensive and less portable than a pMDI alone.
Reduced oropharyngeal deposition compared with a pMDI alone.Prone to reduced or inconsistent dosing because of electrostatic charge associated with plastic spacers.
Improves lung deposition if this is poor with pMDI alone.Special washing instructions.
Useful for maintaining efficient drug delivery during acute exacerbations.Steps in administering drug with a spacer are crucial. Mistakes can lead to reduced, or no drug being inhaled (i.e. multiple actuations into spacer before inhalation, and delay of inhalation after actuation).
Can use tidal breathing if the spacer has a valve.
Some spacers make a noise to indicate that the inhalation flow is too fast.Some children like to make the noise and if they do they will be inhaling too fast.
BA-pMDIsMay be useful for patients who cannot coordinate inhalation and actuation; may be useful for the elderly.Patients sometimes stop inhaling once actuation occurs.
Should not be used with a spacer or VHC.
Breath-actuation does not control inspiratory flow rate, so patients need to be instructed to inhale slowly.
Can only be used with a drug that is dispensed with the device; no substitutions.
DPIsPortable and compact. Many are multi-dose.
Some are single-dose with doses kept separately in sealed packages.Single-dose devices require repeat loading, which can lead to error. Two separate inhalations are required for each dose.
Breath-actuated, so no outside energy source, or propellant, is needed. With no propellant needed, it avoids the possible damaging effects of CFCs to Earth's ozone layer. Also, there is no need to coordinate actuation and inhalation, which is required with a pMDI.DPI delivery can result in high oropharyngeal deposition because a forceful inhalation is needed to aerosolise the particles.
Flow-dependent dose emission for some designs. Poor quality (or no) dose emitted if inspiratory flow is too slow.
Patients need to exhale into the room to functional residual capacity before inhaling from the DPI. Patients should not exhale into the device once the dose has been prepared for inhalation, or the dose could be blown out of the device.
Most multi-dose devices have a dose counter.Patients need to inhale forcefully from the beginning. They should not gradually increase their speed of inhalation.
Short treatment time.Uncertainty of emitted dose during acute exacerbations.
More expensive than pMDIs.
Must be upright when preparing the dose for inhalation. Must be kept upright or turned horizontally during inhalation.
Needs to be stored in a cool and dry place.
NebulisersMay be used at any age.Pneumatic jet devices require an outside energy source and compressor.
Vibrating mesh nebulisers are portable and do not require an outside energy source.
Patient coordination not required.Treatment times can be long.
May be used to dispense drugs that are not available for delivery by pMDI or DPI.Suspensions do not nebulise well.
No propellant needed.Performance (i.e. emitted dose and particle size) varies significantly between devices.
Breath-enhanced nebulisers, dosimetric nebulisers and vibrating mesh nebulisers are much less wasteful of drug than pneumatic jet nebulisers.With pneumatic jet nebulisers, drug can be lost to the surrounding environment during exhalation, exposing caregivers and other personnel to the drug.
Dosimetric nebulisers deliver aerosol during inhalation only, over a proscribed time period, and turn off when dosing is complete.Many pneumatic jet nebulisers are wasteful since a certain volume of solution cannot be aerosolised (i.e. dead volume).
There may be a risk of bacterial contamination if the device is not properly cleaned.
Newer devices (i.e. vibrating mesh nebulisers) are expensive.
  • HFA: hydrofluoroalkane; VHC: valved holding chamber; CFC: chlorofluorocarbon. See Appendix for all product/drug manufacturer details. Reproduced and modified from [9], with permission from the publisher.