INVESTIGATION OF THE PARTICLE-SIZE DISTRIBUTION OF A MODEL INTRAVENOUS EMULSION

The size distribution of a model intravenous (iv) emulsion was investi gated with special regard to the lower size classes. The special inter est in the lower size classes is related to their possible responsibil ity for a number of side effects as well as their possible influence o n pharmacokinetics of incorporated drugs. The particle size distributi on of the unfractionated emulsion observed by photon correlation spect roscopy (PCS) showed no particles with diameters <140 nm. In contrast, a three-dimensional analysis of transmission electron micrographs (TE M) resulted in a mean particle diameter of similar to 68 nm. P-31 NMR experiments revealed that similar to 48 mol% of the emulsifier forms p articles smaller than similar to 100 nm in diameter. The results from TEM observations and NMR spectroscopy suggest that the majority of par ticles by number have diameters <100 nm. PCS measurements of fractiona ted samples of the emulsion, in combination with their chemical analys is, confirmed the predominance of particles with diameters <100 nm. Th e relevance of PGS data analysis for the characterization of unfractio nated iv emulsions, consisting of particles differing in structure and showing a broad size distribution by number, seems limited.