title: Influence of particle size on regional lung deposition--what evidence is there?
abstract: The understanding of deposition of particles in the respiratory tract is of great value to risk assessment of inhalation toxicology and to improve efficiency in drug delivery of inhalation therapies. There are three main basic mechanisms of particle deposition based primarily on particle size: inertial impaction, sedimentation and diffusion. The regional deposition in the lungs can be evaluated in regards to the aerodynamic particle size, in which particle density plays a significant role. In this review paper, we first introduce the available imaging techniques to confirm regional deposition of particles in the human respiratory tract, such as planar scintigraphy, single photon emission computed tomography (SPECT) and positron emission tomography (PET). These technologies have widely advanced and consequently benefited the understanding of deposition pattern, although there is a lack of lung dosimetry techniques to evaluate the deposition of nanoparticles. Subsequently, we present a comprehensive review summarizing the evidence available in the literature that confirms the deposition of smaller particles in the smaller airways as opposed to the larger airways.
authors.affiliation: Division of Pharmaceutics, College of Pharmacy, University of Texas at Austin, Austin, TX, USA.
authors.forename: Thiago C
authors.initials: TC
authors.lastname: Carvalho
authors.forename: Jay I
authors.initials: JI
authors.lastname: Peters
authors.forename: Robert O
authors.initials: RO
authors.lastname: Williams
mesh_terms: D000280:Administration, Inhalation; D016503:Drug Delivery Systems; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000378:metabolism*; D010316:Particle Size; D004364:Pharmaceutical Preparations / Q000008:administration & dosage / Q000737:chemistry; D049268:Positron-Emission Tomography; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D004364:Pharmaceutical Preparations