Metered dose inhalers spacer devices

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. 

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... 

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). 

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. 

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. 

There have been three randomized, double-blind studies in adult asthmatics of the efficacy and safety of a beclomethasone dipropionate-hydrofluoroalkane 134a formulation, equivalent in dose per actuation to the currently marketed beclomethasone dipropionate chlorofluorocarbon products (19-21). Daily doses of beclomethasone dipropionate hydrofluoroalkane 134a 1000 pg over 12 weeks given by metered-dose inhaler (19) or a spacer jet device (20) were equivalent in terms of safety and efficacy compared with beclomethasone dipropionate chlorofluorocarbon 1000 pg. The same was true for doses of 400 pg (21). 

Nine percent of the medication sprayed reaches the bronchioles. Using a spacer increases the delivery of medication to the bronchioles to 21%. The spacer is a funnel-like device that attaches to the mouthpiece of the meter dose inhaler. When administering medication using an inhaler ... 

Figure 9.4 shows a metered dose inhaler attached to a spacer device. The metered dose inhaler is attached to one end of the spacer and the other end contains a mouthpiece which is... 

Figure 9.4 A metered dose inhaler attached to a spacer device.

How to use a metered dose inhaler with the aid of a spacer device... 

Different types of spacer device are available for use with metered dose inhalers but all work in basically the same manner. The spacer usually consists of two parts that slot together with a mouthpiece at one end and an opening for an inhaler at the other. There is a one-way valve which ensures that when a dose of the inhaler is expressed into the spacer the drug is stored in what is basically a holding device. This makes it easier to use a metered dose inhaler successfully as the two actions (pressing down on the metered dose inhaler and inhaling the medication) can be separated into two separate events. 

In particular, the propellant-driven metered-dose inhalers release the aerosol cloud at the very high velocity caused by the pressure of the propellant. The open-mouth technique of inhalation [79] helps to slow down the droplets (and to evaporate the volatile excipients). An even more effective solution is to use spacer devices [4,79-87], in which the aerosol cloud can slowed down, the volatile constituents can evaporate, and any large particles will sediment out. Moreover, the patient can then inhale the remaining aerosol under optimal conditions for pulmonary delivery [4,8,56,79], that is, with a slow inspiratory flow rate. 

Avent, M.L. Gal, P. Ransom, J.L. Brown, Y.L. Hansen, C.J. Comparing the delivery of albuterol metered-dose inhaler via an adapter and spacer device in an in vitro infant ventilator lung model. Ann. Pharmacother. 1999, 33 (2), 141-143. 

Metered-dose inhaler (MDI) Canister held inverted Formulation (CFC, HFA, solution, suspension) Actuator cleanliness Addition of a spacer device Inspiratory flow (slow, deep) Breath-holding Coordinating actuation with inhalation Priming and shaking the device... 

Mandelberg A, Chen E, Noviski N, Priel IE. Nebulized wet aerosol treatment in emergency department Is it essential Comparison with large spacer device for metered-dose inhaler. Chest 1997 112 1501-1505. 

Inhalers are not a very efficient way of delivering medications to the lungs because only 9% of the medication reaches the lungs. The efficiency increases by using a spacer, which delivers 21% of the medication to the lungs. The spacer is a funnel-Kke device that attaches to the mouthpiece of the metered dose inhaler (MDI). The medication is released into the spacer and then the patient inhales slowly and deeply to get the drug into the airway. 

A spacer, a device that attaches directly to the metered-dose inhaler, should be used because a spacer increases the delivery of the drug to the lungs and decreases deposition of the drug on the oropharyngeal mucosa. 

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