Fat emulsion particle size: influence on the clearance rate and the tissue lipolytic activity.

In lipid emulsions for parenteral use the mean particle diameter of the droplets in the 20% emulsions is larger than in the 10% emulsions. In long-chain triglyceride emulsions it is greater than in medium-chain triglyceride emulsions. As the particle diameter decreases, the total interfacial area increases, as does the lipoprotein lipase (LPL) and hepatic lipase (HL) activity. For a given quantity of triglycerides and phospholipids the lipolytic activity is proportional to the total interfacial area. A doubling of the phospholipid concentration is accompanied by a small reduction in the activity of both enzymes. In going from long-chain to medium-chain triglycerides, there is an acceleration in the clearance rate of infused lipid. For a similar emulsion, the clearance rate decreases as the particle size decreases. It seems plausible that the larger the mean droplet diameter, the greater the participation of the reticuloendothelial system in the clearance.