EurekaMag.com logo
+ Site Statistics
References:
52,725,316
Abstracts:
28,411,598
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Development of a systematic theory of suspension inhalation aerosols ii. aggregates of monodisperse particles nebulized in polydisperse droplets






International Journal of Pharmaceutics (Kidlington) 41(1-2): 147-158

Development of a systematic theory of suspension inhalation aerosols ii. aggregates of monodisperse particles nebulized in polydisperse droplets

Using the previously developed statistical framework to study the aggregation of primary drug particles in droplets formed on nebulization of supensions, we have computed the expected size distributions of clusters of monodisperse primary drug particles obtained after drying of log-normally distributed polydisperse aerosol droplet sprays. In systems with a high ratio of droplet to primary particle diameters and relatively high average number of particles per droplet, the cluster size distributions were found to be essentially log-normal with the same geometric standard deviations as the droplets, and the mass median (aerodynamic) diameters were accurately predictable on the basis of assumption of uniform distribution of the solid throughout the liquid phase. In systems where the average number of primary particles per droplet was less than one, the cluster size distributions showed markedly non-linear behaviour on log-normal probability graphs. However, the mass median (aerodynamic) diameters could still be predicted quite reliably assuming uniform distribution of the solid among the fraction of the droplets expected to be occupied by the solid particles (i.e. excluding the empty droplets from the calculations). When the ratio of the droplet to primary particles was small and the concentration of the suspension was high, the size distributions of the aggregates deviated markedly from the log-normal function, particularly when the droplet sprays were narrowly distributed. Calculation of the mass median (aerodynamic) diameters and geometric standard deviations using the uniform distribution assumption could lead to grossly erroneous results in these systems. The reason for this behaviour is that (i) spherical particles cannot fill space completely and (ii) a significant portion of the log-normally distributed droplets is too small to accommodate the number of primary particles which would be computed for these droplets on purely statistical grounds. This 'exclusion' effect, however, becomes marked only at high concentrations which are beyond the range used in current therapeutic aerosols and outside the regions of validity of some of the assumptions of the present theory. Thus, assuming uniform distribution of solid in the droplets of aerosol sprays, it is possible to estimate the significance of formation of solid aggregates arising for purely statistical reasons (i.e., without taking into account any forces of attraction causing flocculation or coagulation). Outside the regions of validity of the assumption of uniform distribution, the full computational model developed in this paper has to be used to find the median size and the shape of the distribution of the solid clusters.

Accession: 005132124

DOI: 10.1016/0378-5173(88)90147-0

Download PDF Full Text: Development of a systematic theory of suspension inhalation aerosols ii. aggregates of monodisperse particles nebulized in polydisperse droplets



Related references

Gonda, I., 1985: Development of a systematic theory of suspension inhalation aerosols i. a framework to study the effects of aggregation on the aerodynamic behavior of drug particles. When a suspension of drug particles is nebulized, the number of particles in a droplet depends on its size and on the relative sizes of the particles and the concentration of the suspension. Therefore, the drug particle size distribution after aer...

Xi, J.; Yuan, J.Eddie.; Si, X.April., 2016: Simulation study of electric-guided delivery of 0.4┬Ám monodisperse and polydisperse aerosols to the ostiomeatal complex. Despite the high prevalence of rhinosinusitis, current inhalation therapy shows limited efficacy due to extremely low drug delivery efficiency to the paranasal sinuses. Novel intranasal delivery systems are needed to enhance targeted delivery to t...

Thomas, R.L.; Raabe, O.G., 1978: Regional deposition of inhaled 137 Cs-labeled monodisperse and polydisperse aluminosilicate aerosols in Syrian hamsters. Two groups of eighty Syrian hamsters were exposed to aerosols of 137Cs-labeled fused aluminosilicate particles. One group was exposed to a monodisperse aerosol with AMAD (activity median aerodynamic diameter) of 1.53 micron and sigma g (geometric...

Snipes, M.B.; Boecker, B.B.; McClellan, R.O., 1983: Retention of monodisperse or polydisperse aluminosilicate particles inhaled by dogs, rats, and mice. This study compared long-term retention of 134Cs-labeled fused aluminosilicate particles inhaled by three animal species. Dogs, rats, and mice were briefly exposed to 0.7-, 1.5-, or 2.8-micron activity median aerodynamic diameter (AMAD) monodisper...

Bushell; Amal, 1998: Fractal Aggregates of Polydisperse Particles. In this work we examine structural effects of particle polydispersity on fractal aggregates by performing DLCA simulations with multiple primary particle sizes. We show that the fractal structure and the form of the cutoff function that describes...

Kotrappa, P.; Moss, O.R., 1971: Production of relatively monodisperse aerosols for inhalation experiments by aerosol centrifugation. Health Physics 21(4): 531-535

Malik, S.K., 1973: Decrease in specific airway conductance following inhalation of nebulized aerosols. Indian Journal of Chest Diseases 15(4): 272-275

Newman S.P.; Pellow P.G.D.; Clarke S.W., 1986: Droplet size distributions of nebulized aerosols for inhalation therapy. Jet nebulisers are used commonly for aerosol therapy in patients with asthma and bronchitis, but the manufacturers' information regarding aerosol droplet size is often inadequate. In this study, mass median diameter, geometric standard deviat...

Park, C.Ho.; Chung, N-Oh.; Lee, J., 2011: Monodisperse red blood cell-like particles via consolidation of charged droplets. Recently, researchers have tried to produce non-spherical and anisotropic particles to be used in the next generation of multi-functional materials. Of key interest is the red blood cell-like particle. The torus structure was produced under the re...

Kotrappa, P.; Wilkinson, C.J.; Boyd, H.A., 1972: Technology for the production of monodisperse aerosols of oxides of transuranic elements for inhalation experiments. Health Physics 22(6): 837-843