Regional deposition

Determination of regional deposition is nsually based on measurements of particle removal from the respiratory tract after short-term steady-state breathing of radio-labeled particles relatively insoluble in body fluids. First of all, total deposition can be partitioned into extrathoracic and thoracic components by external detection of the amount of radiotracer deposited in head and neck and in thorax immediately after particle administration with a number of scintillation detectors placed around head or thorax as schematically shown in Fig. 9. Thoracic deposition can then be 

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It has recently been recognized that a fraction of particles deposited on surfaces of ciliated thoracic airways is not removed from these airways within 40 h but retained for longer periods (4). This long-term retention phenomenon was observed for particles smaller than 6 pm in diameter. Although particle removal from thoracic airways is therefore overestimated by the radiotracer technique, it affects bronchial deposition by less than 10%. 

When an aerosol enters the respiratory tract, its particles first experience inertial transport onto airway surfaces in the extrathoracic and upper bronchial region. 

There are several approaches to characterize nasal deposition by mathematical (120,122)orby empirical models (163,165-168,173,184,188,189). For particles of 1 (Am or larger, Rudolf et al. (168) estimated inspiratory particle collection efficiency of the nose ( et-n) by 

This empirical model assumes the inspiratory flow rate to be constant. 

Deposition of particles of the thermodynamic size range has not been studied extensively in humans. Cheng and co-workers (185) measured deposition efficiencies for 4-, 8-, 20-, and 150-nm particles in ten healthy adult, male volunteers. For nose-in mouth-out breathing at flow rates of 333 cm s, deposition fractions for these particle sizes were 36.7 10.6 (mean SD), 21.2 8.9, 11.1 7.7, and 5.2 3.8%. However, because expiratory deposition in the mouth is not negligible for particles in the thermodynamic domain, these values overestimate nasal deposition. The large SD values indicate that intersubject deposition variability is notable in the thermodynamic domain. Mean nasal deposition, as de- 

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Figure 4. Regional Deposition Rate of Sulphate for North America, 1980, adapted from reference 17.

Chan TL, Lippman M. 1980. Experimental measurements and empirical modeling of the regional deposition of inhaled particles in humans. Am Ind Hyg Assoc J 47 399-408. 

Chan, T. L. and M. Lippmann, Experimental Measurements and Empirical Modelling of the Regional Deposition of Inhaled Particles in Humans, Amer. Ind. Hvg. Assoc. J. 41 399-409 (1980). 

Lippmann, M. (1977). Regional deposition of particles in the human respiratory tract , Section 9, page 213 in HANDBOOK OF PHYSIOLOGY, Lee, H. D. K. Sect. Ed., (American Physiological Society, Bethesda, Md.). 

Park, S-U., Lee, Y-H. (1999b). Mapping of base cation deposition in South Korea. In Proceedings of 5th International Joint Seminar on Regional Deposition Processes in Atmosphere, Seoul, October 12-16, pp. 177-188. 

Stahlhofen, W., Gebhart, J. and Heyder, J. (1980). Experimental determination of the regional deposition of aerosol particles in the human respiratory tract. Am. Ind. Hyg. Assoc. J. 41 385-398. 

Colthorpe P, Farr SJ, Smith IJ, Wyatt D, Taylor G (1995) The influence of regional deposition on the pharmacokinetics of pulmonary delivered human growth hormone in rabbits. Pharm Res 12 356-359. 

Pang Y, Sakagami M, Byron PR (2005) The pharmacokinetics of pulmonary insulin in the in vitro isolated perfused rat lung implications of metabolism and regional deposition. Eur J Pharm Sci 25 369-378. 

Chan, El.K., Phipps, P.R., Gonda, L, Cook, P., Fulton, R., Young, L, and Bautovieh, G., Regional deposition of nebulized hypodense non-isotonie solutions in the human respiratory traet, Eur. Resp. J., 17 1483-1489 (1994). 

Altshuler, B. Calculation of regional deposition of aerosol in the respiratory tract. Bull. Math. Biophys. 21 257-270, 1959. 

Raabe OG et al Regional deposition of inhaled monodisperse coarse and fine particles in small laboratory animals. Ann Occup Hyg 32, Suppl 1 53-63, 1988... 

Used to derive a chronic inhalation Minimal Risk Level (MRL) of 2 x 10" mg/m nickel for soluble nickel salts dose adjusted for intermittent exposure (6/24 hours, 5/7 days), multiplied by the Regional Deposited Dose Ratio (0.9714 for pulmonary region deposition mass median aerodynamic diameter [MMAD] = 2.5 pm, sigma = 2.4 pm), and divided by an uncertainty factor of 30 (3 for extrapolation from animals to humans, and 10 for human variability). 

The exposure concentration was adjusted for intermittent exposure (6 hours/24 hours, 5 days/7 days). A regional deposition ratio of 0.9714 for the pulmonary region for particle size 2.5 pm and sigma 2.4 was used to extrapolate from particle deposition in rats to deposition in humans... 

Sangwan, S., IM. Agosti, L.A. Bauer, B.A. Otulana, R.I Morishige, D.C. Cipolla, ID. Blanchard, and G.C. Smaldone, Aerosolized protein delivery in asthma gamma camera analysis of regional deposition and perfusion. J Aerosol Med, 2001. 14(2) 185-95. 

The Mass Median Aerodynamic Diameter (MMAD) was reported as a lower limit of 0.8 pm and an upper limit of 1.2 pm for an average of 1.0 pm (pg 33 Hartman 1990). The Geometric Standard Deviation (GSD) was reported as a lower limit of 1.2 pm and an upper limit of 1.5 pm for an average of 1.35 or 1.4 pm. The Regional Deposited Dose Ratio (RDDR) from Table HI under the ER (Extrarespiratory effects) column is... 

Table IX. Regional Deposition of Fission Products by Nuclear Event ...

Hallworth, G. W., Padfield, J. M. Comparison of the regional deposition in a model nose of a drug discharged from metered-aerosol and metered-dose nasal delivery systems. J Allergy Clin Immunol 77(2) 348-353 (1986). 

Black, A. Pritchard, J.N. (1984) A comparison of the regional deposition and short term clearance of tar particulate matter from cigarette smoke with that of 2.5 pm polystyrene microspheres. Journal of Aerosol Science, 15, 224-7. 

Foord, N., Black, A. Walsh, M. (1978) Regional deposition of 2.5-7.5 pm diameter particles in healthy male non-smokers. Journal of Aerosol Science, 9, 343-57. 

Fry, F.A. Black, A. (1973) Regional deposition and clearance of particles in the human nose. Journal of Aerosol Science, 4,113-24. 

Pritchard, J.N. et al. (1980) A comparison of the regional deposition of monodisperse polystyrene particles in the respiratory tract of healthy male smokers and non-smokers. In Aerosols in Science, Medicine and Technology, ed. W. Stober D. Hochrainer. Schmallenberg, F.R.G. Gesellschaft fiir Aerosolforshung. 

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