Discussion and Considerations for the Excretion Mechanism of Perfluorochemical Emulsion

Abstract

It has been assumed that a mononuclear phagocyte system is related to the excretion of PFC emulsions: PFC particles are phagocytized by blood monocytes to be expelled through the lung alveoli. This monocyte-related mechanism may well explain excretion at an early stage when PFC particles are abundant in the blood stream. It does not, however, fully explain the manner by which PFC cells are released from the RES cells into the blood stream and into the adipose tissue. To explain this, the following mechanism has been proposed and discussed based on some experimental results. PFC emulsion particles taken up by the RES organs, are stripped at their surfactant layers in the cells and move across the cell membranes to the blood vessels and into other tissues such as adipose, at a rate that depends on the lipophilicity of the PFC's. In the blood stream, PFCs are delivered by lipoproteins to the lung and excreted into the expired air. Pharmacokinetical analysis with a compartmental model for the excretion also supported this proposed mechanism.

Probing different perfluorocarbons forin vivoinflammation imaging by19F MRI: image reconstruction, biological half-lives and sensitivity

“…PFCs are primarily released from the organism by exhalation via the lung, and the rate depends on their physicochemical properties, such as molar mass, boiling point, vapor pressure, lipophilicity and permeability through the membrane . However, after the injection of PFC emulsions, several competing processes take place which will affect retention in the organism: (i) nanoparticles injected into the bloodstream are quickly taken up by circulating monocytes/macrophages, which then migrate into inflamed regions or end up in the organs of the reticuloendothelial system; of note, the rate of phagocytosis increases with increasing particle size ; (ii) the PFCs can directly vaporize from the droplets, a process mainly determined by PFC properties such as vapor pressure and molar mass ; (iii) a direct diffusion of emulsified particles into inflammatory foci via leaky endothelium may occur , which primarily depends on the properties of the emulsion, e.g.…”

Synthetic Oxygen Transport Fluids Based on Perfluorochemicals: Applications in Medicine and Biology

“…PFCs are excreted primarily by expiration from the lungs [51] and this again depends on the MW and hence, vapour pressure, of the individual molecules [14,15]. There appears to be little influence by other factors, such as the presence of cycles or heteroatoms, on the rate of PFC excretion [15], A small loss of PFCs from the body can also occur by transpiration through the skin.…”

The Elimination Peculiarities of Perfluorocarbon Emulsions Stabilized with Egg Yolk Phospholipid

“…The elimination rate during the second stage is much lower (2,4). During the first stage the elimination of the emulsion directly from the blood stream takes place (with the participation of phagocytes); during the second stage the elimination of FDC accumulated in organs takes place.…”