Half life and changes in the composition of a perfluorochemical emulsion within the vascular system of rats

The decline of the concentration of perfluorochemicals (PFC) after a single injection of three different doses was studied in the circulation of rats. The doses used amounted to 4.4, 10 and 14 g/kg body weight of Fluosol-DA, an emulsion of 7 parts of perfluorodecalin (FDC) and 3 parts of perfluorotripropylamine (FTPA). This also allowed testing of the composition of the emulsion remaining in the circulation and of that found in the liver. After two days a decrease of the half life from 34.0 +/- 0.7 to 17.1 +/- 4.3 h was found within the circulation at the highest dose. At the same time a change in the composition of the emulsion in the blood stream occurred, favouring the fraction of FTPA. FTPA increased from 28.3 +/- 1.4 to 54.4 +/- 8.1% on the fourth day. Whereas in the cells of the liver PFC droplets may be broken up, freed from their surfactant layer and handled according to their individual components, for PFC in the blood stream an unchanged composition should be assumed. Both results, the decreasing half life and the change in composition of the circulating emulsion may best be explained by a shrinking and instability of the emulgator film, showing the necessity for development of a superior surfactant.