Metered-dose inhaler spacers

R. Ahrens, C. Lux, T. Bahl, and S. H. Han, Choosing the metered-dose inhaler spacer or holding chamber that matches the patient s need evidence that the specific drug being delivered is an important consideration, J. Allergy Clin. Immunol. 96 288 (1995). 

Hanania NA, Wittman R, Kesten S, Chapman KR. Medical personnel s knowledge of and ability to use inhaling devices metered dose inhalers, spacer chambers, and breath actuated dry powder inhalers. Chest 1994 105 111-116. 

To properly instruct the patient in administration of drug via a metered-dose inhaler, the nurse must be aware of general instructions for use for all metered-dose inhalers and three common methods of rise holding the lips around the mouthpiece, holding the inhaler away from the mouth, and rising a spacer or extender. 

Drug dispersion using a metered dose-inhaler with and without a spacer. (Adapted from the American Lung Assoaation. [1993], Understanding lung medications How they work—how to use them, p. 5)... 

A metered dose inhaler with spacer is equivalent to nebulized therapy, may have a more rapid onset, and fewer adverse effects ° 4-8 puff doses... 

The most common adverse effects from inhaled corticosteroids include oropharyngeal candidiasis and hoarse voice. These can be minimized by rinsing the mouth after use and by using a spacer device with metered-dose inhalers. Increased bruising and decreased bone density have also been reported the clinical importance of these effects remains uncertain.1,2,19... 

Albuterol is the preferred bronchodilator for treatment of acute exacerbations because of its rapid onset of action. Ipratropium can be added to allow for lower doses of albuterol, thus reducing dose-dependent adverse effects such as tachycardia and tremor. Delivery can be through metered-dose inhaler (MDI) and spacer or nebulizer. The nebulizer route is preferred in patients with severe dyspnea and/or cough that would limit delivery of medication through an MDI with spacer. If response is inadequate, theophylline can be considered however, clinical evidence supporting its use is lacking. 

Newman, S.P., Clark, A.R., Talaee, N., and Clarke, S.W., Pressurized aerosol deposition in the human lung with and without an open spacer device. Thorax, 44 706-710 (1989). Newman, S.P., Clark, A.R., Talaee, N., and Clarke, S.W., Lung deposition of 5 mg Intal from a pressurized metered dose inhaler assessed by radiotracer technique, Int. J. Pharm., 74 203-208 (1991). 

Aerosolized medications are available as pressurized or breath-actuated metered-dose inhalers (MDIs), dry powder inhalers (DPIs), and nebulized or wet aerosols. Most inhaled medications currently used are available as metered-dose inhalers (Table 3). For the patient who has difficulty to coordinate activation of a MDI, a spacer improves delivery. Spacers reduce deposition of the drug in the... 

Thorsson L, Edsbacker S. Lung deposition of budesonide from a pressurized metered-dose inhaler attached to a spacer. Eur Respir J 1998 12(6) 1340-5. 

Goldberg S, Einot T, Algur N, Schwartz S, Greenberg AC, Picard E, Virgihs D, Kerem E. Adrenal suppression in asthmatic children receiving low-dose inhaled budesonide comparison between dry powder inhaler and pressurized metered-dose inhaler attached to a spacer. Ann Allergy Asthma Immunol 2002 89(6) 566-71. 

G. Dickens, D. Wermeling, C. Matheney, W. John, W. Abramowitz, S. Sista, T. Foster, and C. S., Flunisolide administered via metered dose inhaler with and without spacer and following oral administration, J. Allergy Clin. Immunol. 103, S135 (1999) 703 S132 (1999). 

O. Selroos, and M. Halme, Effect of a volumatic spacer and mouth rinsing on systemic absorption of inhaled corticosteroids from a metered dose inhaler and dry powder inhaler, Thorax 46 891 (1991). 

S. P. Newman, J. Brown, K. P. Steed, S. J. Reader, and H. Kladders, Lung deposition of fenoterol and flunisolide delivered using a novel device for inhaled medicines Comparison of RESPIMAT with conventional metered-dose inhalers with and without spacer devices, Chest 113 951 (1998). 

Patients who have difficulty in coordination with inhalers can use a spacer device. These remove the need for coordination between actuation of a pressurised metered dose inhaler and inhalation. The spacer device reduces the velocity of the aerosol and subsequent impaction on the oropharynx. In addition, the device allows more time for evaporation of the propellant so that a larger proportion of the particles can be inhaled and deposited in the lungs. The size of the spacer is important, the larger spacers with a one-way valve (Nebuhaler, Volumatic) being most effective. Spacer devices are particularly useful for patients with poor inhalation technique, for children, for patients requiring higher doses, for nocturnal asthma, and for patients who have poor coordination. 

Metered dose inhalers - with or without spacers. 

The key features of metered dose inhalers, dry powder inhalers and spacers are listed in Table A17.2. 

Asmus, M. J., Liang, J., Coowanitwong, I., and Hochhaus, G. (2004), In vitro performance characteristics of valved holding chamber and spacer devices with a fluticasone metered-dose inhaler, Pharmacotherapy, 24,159-166. 

Hindle, M., and Chrystyn, H. (1994), Relative bioavailability of salbutamol to the lung following inhalation using metered dose inhalation methods and spacer devices, Thorax, 49,549-553. 

Smyth, H. D., Beck, V. P, Williams, D., and Hickey, A. J. (2004),The influence of formulation and spacer device on the in vitro performance of solution chlorofluorocarbon-free propellant-driven metered dose inhalers, AAPS PharmSciTech, 5, E7. 

Metered dose inhaler has been the most popular aerosol delivery device for the treatment of respiratory diseases, which is attributable to its portability and simple operation. Although seemingly easy to use, the MDI is a sophisticated device in design. The drug(s) are suspended or dissolved in a liquefied propellant system, which may also contain excipients such as cosolvents or surfactants. The formulation is kept pressurized in a small canister, sealed with a metering valve. Upon actuation through an actuator, the valve opens and the metered dose is dispensed as an aerosol spray from the expansion and vaporization of the propellant under ambient pressure. The inhalers may be used alone or with spacer devices, the electrostatic issues of which are considered in a later section. The present discussion focuses on the inherent charging of particles produced from MDIs. 

Newman, S.P. Spacer devices for metered dose inhalers. Clin. Pharmacokinet. 2004, 43 (6), 349-360. 

For the use of an inhaled medication (e.g., p2-agonists, corticosteroids, antivirals, cromolyn, etc.), it is crucial for the child and parents to understand the mechanism of the metered dose inhaler (MDI) or nebulizer, if used. The package insert should also be reviewed for information about the specific drug product. A decision may also need to be made as to whether a spacer may be needed for use with the medication canister. 

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