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Inhaler devices

Three types of inhaler devices exist to deliver inhaled corticosteroids (ICSs) to the lungs:

Pressurized metered-dose inhalers (pMDIs) 

These dispense a measured dose of drug through the use of a propellant. Hydrofluoroalkane (HFA) suspensions and solutions are both delivered using pMDIs which, compared with dry-powder inhalers (DPIs), produce smaller particles of a more consistent size. HFA suspension pMDIs contain particles around 2.4μm in diameter, while HFA solution pMDIs contain particles with an average diameter of 1.1μm. This small particle diameter allows HFA solution pMDIs to exhibit high drug deposition in the lungs and distribution to the small airways.1,2 HFA solution pMDIs are also associated with other properties, such as a slower spray velocity and softer plume, than HFA suspension pMDIs.3

Watch the video at the bottom of this page to see how these properties can help reduce impaction in the oropharynx, and subsequently the incidence of oropharyngeal adverse events.

As with all types of asthma inhaler, it is important to use correct technique and coordination to ensure the desired dose is delivered.
 
Dry-powder inhalers (DPIs) 

Correct inhaler technique is essential for patients to inhale an accurate dose of ICS using a DPI. This is because the particle size distribution of these inhalers may be related to the rate at which peak inspiratory flow (PIF) is achieved.5 PIF has to be reached within 1 second to ensure that a reasonable proportion of small particles is inhaled. Some patients may not be able to generate enough force to properly activate these devices.6

Wet nebulizers 

These devices dispense a fine mist of drug-filled droplets, which are inhaled through a mask or mouthpiece over 5–10 minutes. Nebulizers are expensive, time consuming to use and require regular maintenance.7 Moreover, there are data to suggest that these devices may be no more effective than pMDIs used with spacers.

As physicians, it is important to select the correct inhaler device according to an individual patient’s abilities and preferences (Table 1).

16 fig 1Inhalers and patient characteristics
SMI: soft-mist inhaler
Table 1: Suitability of the main inhaler device types, categorized by patient ability6
Adapted from Voshaar T, Kostev K, Rex J et al. A retrospective database analysis on persistence with inhaled corticosteroid therapy: comparison of two dry powder inhalers during asthma treatment in Germany. Int J Clin Pharmacol Ther 2001;50:257-264. 
 

A comparison of spray plumes between an HFA solution and HFA suspension pMDI


References
  1. Newman S, Salmon A, Nave R, et al. High lung deposition of 99mTc-labeled ciclesonide administered via HFA-MDI to patients with asthma. Respir Med 2006;100:375-84.
  2. Leach CL, Bethke TD, Boudreau RJ, et al. Two-dimensional and three-dimensional imaging show ciclesonide has high lung deposition and peripheral distribution: a nonrandomized study in healthy volunteers. J Aerosol Med 2006;19:117-26.
  3. Nave R, Mueller H. From inhaler to lung: clinical implications of the formulations of ciclesonide and other inhaled corticosteroids. Int J Gen Med 2013;6:99-107.
  4. Bateman ED, Linnhof AE, Homik L, et al. Comparison of twice-daily inhaled ciclesonide and fluticasone propionate in patients with moderate-to-severe persistent asthma. Pulm Pharmacol Ther 2008;21:264-75.
  5. Everard ML, Devadason SG and Le Souef PN. Flow early in the inspiratory manoeuvre affects the aerosol particle size distribution from a Turbuhaler. Respir Med 1997;91:624-8.
  6. Chapman KR, Voshaar TH and Virchow JC. Inhaler choice in primary practice. Eur Respir Rev 2005;14:117-22.
  7. The Global Initiative for Asthma (GINA) Global Strategy for Asthma Management and Prevention. Available from: http://www.ginasthma.org/2012
  8. Cates CJ, Welsh EJ and Rowe BH. Holding chambers (spacers) versus nebulisers for beta-agonist treatment of acute asthma. Cochrane Database Syst Rev 2013;9:CD000052.
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