Metered-dose inhaler chambers

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). 

Berry, J., Heimbecher, S., Hart, J. L., and Sequeira, J. (2003), Influence of the metering chamber volume and actuator design on the aerodynamic particle size of a metered dose inhaler, Drug. Dev. Ind. Pharm., 29, 865-876. 

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. 

Newhouse, M. T., Nantel, N. P., Chambers, C. B., Pratt, B., and Parry-Billings, M. (1999), Clickhaler (a novel dry powder inhaler) provides similar bronchodilation to pressurized metered-dose inhaler, even at low flow rates, Chest, 115, 952-956. 

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. 

Finlay WH, Zuberbuhler P. In vitro comparison of beclomethasone and salbutamol metered-dose inhaler aerosols inhaled during pediatric tidal breathing from four valved holding chambers. Chest 1998 114 1676-1680. 

Wildhaber JH, Dore ND, Wilson JM, Devadason SG, LeSouef PN. Inhalation therapy in asthma nebulizer or pressurized metered-dose inhaler with holding chamber In vivo comparison of lung deposition in children. J Pediatr 1999 135 28-33. 

Vidgren P, Vidgren M, Paronen P, Vainio P, Nuutinen J. Effects of inspirease holding chamber on the deposition of metered dose inhalation aerosols. Enr J Drug Metab Pharmacokinet 1991 3 419 25. 

The working principle of this device is a mechanical inhalation from the DPI into a spacer (Fig. 8). This inhalation is caused by the release of a spring-loaded piston nndemeath the spacer chamber. The inhalation draws the metered dose as an aerosol from the DPI into the spacer. After inhalation, the piston is compressed npon the spring and locks in place, ready for the next use. As a consequence of the standardized natnre of the mechanical actuation, there is no re-qnirement for forced inspiration, and repeatability of dosing is high. The use of a vertical spacer position opposed to the traditional horizontal position increases the sedimentation distance, which prolongs the half-life of the aerosol and thns increases the time available for inhalation. 

Pulvinal (Chiesi, Italy) is a multidose reservoir inhaler containing 100 doses of powder mixture. A protecting cap provides a moistureproof barrier. On rotation of the mouthpiece, a dose is metered volumetrically into a cavity and then transferred into an aerosolizing chamber. Upon inhalation, air is drawn through the aerosolizing chamber and the aerosol is transported out through the mouthpiece. 

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