Lung deposition

Animal model Am specie s Exposure Exposure concentration3 Aerosol AMAD (pm GSD) Lung deposition (percent of dose) Lung retention or absorption half-time15 Reference... 

Animal Am Exposure AMAD Lung deposition absorption ... 

Lung deposition patterns and the relative contributions of the fecal and urinary pathways vary with the aerosol particle size. Evidence for this is provided by a study in which dogs inhaled Am02 aerosols having... 

DOE. 1985b. Factors affecting the assessment of lung depositions of transuranics. Washington, DC ... 

James AC. 1878. Lung deposition of sub-micron aerosols calculated as a function of age and breathing rate. In National Radiological Protection Board annual Research and Development Report. National Radiological Protection Board. Harwell, United Kingdom,71-75. 

The factors governing lung deposition may be divided into those related to the physicochemical properties of the droplets or particles being delivered, the mechanical aspects of aerosol dispersion usually associated with the delivery device, and the physiological and anatomical considerations associated with the biology of the lungs. 

C. Physiological and Anatomical Features Governing Lung Deposition... 

Most lung deposition models are based on the influence of particle size on aerosol deposition. Breathing parameters, such as breathing frequency and tidal volume, play a key role in lung deposition [15]. Table 2 shows the breathing parameters for healthy male volunteers subjected to various levels of exercise on a bicycle ergometer [16], There are known differences in these parameters based on gender, age, and disease... 

There have been attempts to conduct in vitro experiments in a manner that gives more meaningful data with regard to lung deposition. These methods, which are loosely based on inertial impaction, utilize inspiratory flow cycles rather than fixed flow... 

Drug delivery to the respiratory tract has been characterized in the past decade by an increase in knowledge of drug droplet or particle manufacture, behavior, aerosol dispersion, lung deposition and clearance. The number of diseases for which aerosol therapy may be applicable has increased dramatically. The pharmaceutical scientist is no longer limited to pulmonary diseases as therapeutic targets. Substantial progress has been made in every area of pharmaceutical aerosol science, and it is anticipated that this will ultimately lead to many new therapies. 

TB Martonen, I Katz, K Fults, AJ Hickey. Use of analytically defined estimates of aerosol respirable fraction to predict lower lung deposition. Pharm Res 9 1634-1639, 1992. 

AJ Hickey. Lung deposition and clearance of pharmaceutical aerosols What can be learned from inhalation toxicology and industrial hygiene Aerosol Sci Technol 18 290-304, 1993. 

Diffusion is the dominant mechanism of lung deposition for radon daughter aerosols. It is generally assumed that airflow is laminar in the smaller airways and that deposition in each airway generation can be calculated adequately (Chamberlain and Dyson, 1936 Ingham, 1975). However, there is no such consensus on the treatment of deposition in the upper bronchi. Some authors (Jacobi and Eisfeld, 1980 NCRP, 1984) have considered deposition to be enhanced by secondary flow, on the basis of experimental results (Martin and Jacobi, 1972). It has been shown that this assumption reduces the calculated dose from unattached radon daughters by a factor of two (James, 1985). 

Studies have shown that in order to clear the oropharyngeal impaction barrier (comprising the mouth, throat, and pharynx), particles with aerodynamic diameters smaller than 5 pm are required [3,4]. Only particles with aerodynamic diameters less than 3 pm reach the terminal bronchi and the alveoli in significant numbers [5]. Therefore, the particle diameter required to be produced by the delivery system depends to a great extent on the intended target lung tissue. Lung deposition is also affected substantially by the specific inhalation dynamics of the patient, which in turn are influenced by the delivery device. This article addresses various attributes of the dry powder inhalation product, from intrinsic material properties to final product performance. 

To measure lung deposition by imaging, the aerosol must be first labelled or tagged with a suitable radionuclide. Radiolabelling techniques have been developed for current inhalation products including nebulizers, propellant-driven metered dose inhalers, and dry powder inhalers. 

Salbutamol Radiolahelling method development, simultaneous measurement of lung deposition and hronchodilator response 16... 

Salbutamol and fenoterol Development of radiolabelling method and lung deposition 24... 

Flunisolide and fenoterol Lung deposition and effect of a spacer 25... 

Terbutaline sulfate Development of radiolabelling method for Turbu-haler in lung deposition study 31... 

Nedocromil sodium Lung deposition study and comparison with an MDI 34... 

Budesonide Lung deposition in children with cystic firbrosis 38... 

Disodium cromoglycate Lung deposition comparison between a conventional MDI and a new DPI 34... 

Snell, N.J.C., and Ganderton, D., Assessing lung deposition of inhaled medications, Resp. 

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