Aerosol delivery efficiency

Many reviews on the relevant technical aspects for drug nebulization are available (e.g. [43 5]. The greatest disadvantages of nebulizers are their poor deposition efficiency (see Section 3.11) and low output rate (e.g. [46]). Several developments have been reported to improve their efficacy, like the use of open vents or breath-assisted open vents [47] and adapted aerosol delivery [48]. A renewed interest in nebulizer therapy may also come from the generation of special aerosols, such as hposomes [49]. 

Stein, S. W., and Myrdal, P. B. (2006), The relative influence of atomization and evaporation on metered dose inhaler drug delivery efficiency, Aerosol Sci. Tech., 40,335-347. 

The delivery efficiency, or the nebulizer output, can be expressed in many different ways, as widely documented in the literature. Sometimes it is represented as the volume output, or solution mass output. However, it is more practical to use the drug mass emitted from the nebulizer at or near the mouthpiece to estimate the nebulizer output, because the amount of aerosolized drug mass at this point in the system is the best measure of how much drug the patient has available to inhale. 

Nebulizers fitted with a T-mouthpiece have an unrestricted flow of ambient air passing through the nebulizer output, supplying inhaled air flow, which effectively increases drug output. In vented nebulizers, the inhaled air must flow through the droplet production region. Therefore, the breathing pattern of the patient has an effect on the aerosol characteristics produced by such devices. The delivery efficiency of... 

The nominal dose is defined as the amount of active drug metered as a liquid solution from the device. The emitted dose is the amount of aerosolized drug obtained at the exit of the mouthpiece, and the device delivery efficiency is the ratio of the emitted to nominal dose. The mean delivery efficiency was approximately 94% (SD = 3.2) with a 3.4% coefficient of variation. The delivery efficiency for the two devices tested was 93% (SD = 3.60, n = 5) and 95% (SD = 2.8, n = 5), respectively. The intradevice variation was 1.7% (coefficient of variation, n = 2 prototypes). There were no significant differences p > 0.05) in the drug mass output within the device throughout its life cycle, nor between devices tested in the study. 

Schuster, J.A. Farr, S.J. Cipolla, D. Wilnbanks, T. Resell, J. Lloyd, P. Gonda, I. Design and performance validation of a highly efficient and reproducible compact aerosol delivery system AERx . In Respiratory Drug Delivery VI Dalby, R.N., Byron, P.R., Farr, S.J., Eds. Interpharm Press, 1998 83-90. 

The aerodynamic size distribution is a key parameter affecting the regional distribution, and hence the absorption, of macromolecular drugs from the lung. The synchronization of optimum breathing and aerosol delivery appears to be a prerequisite for efficient and reproducible delivery the key parameters to control are listed in Table 1. 

Advances in the equipment for the administration of aerosol medication to horses have facilitated the widespread use of inhalation therapy in equine medicine. Newer aerosolization devices ease administration and make pulmonary drug delivery efficient. Aerosol therapy is likely to become the mainstay of treatment for horses with heaves and may prove beneficial in the treatment of infectious respiratory disease in horses. 

Stein SW and Myrdal PB. The Relative Influence of Atomization and Evaporation on Metered Dose Inhaler Drug Delivery Efficiency. Aerosol Science and Technology 2006 40 335-347. 

Spacers are more efficient than nebulizers for aerosol delivery to a ventilated patient. 

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