American Journal of Clinical Nutrition, Vol 16, 29-36, Copyright © 1965 by The American Society for Clinical Nutrition, Inc.

Toxicity Testing of Fat Emulsions

I. Tolerance Study of Long-Term Intravenous Administration of Intralipid in Rats

¹ From the Department of Physiology, Vanderbilt University School of Medicine, Nashville, Tennessee and the U. S. Army Medical Research and Nutrition Laboratory, Denver, Colorado

The present work was designed to study the tolerance of rats to a soybean oil emulsion, Intralipid, for intravenous administration. Forty-six male rats weighing about 220 gm. were divided into two groups. Twenty-four rats were given 6.0 gm. of fat per kg. of body weight per day as a 20 per cent emulsion and twenty-two were given 2.0 gm. of fat per kg. per day as a 10 per cent preparation. The fat emulsion was injected intravenously through the tail vein daily for thirty consecutive days. The 10 per cent emulsion (2.0 gm. of fat per kg. group) was given once a day while the 20 per cent emulsion (6.0 gm. of fat per kg. group) was administered twice a day in two equally divided doses. Food (Purina rat chow) and water were allowed ad libitum. Observations were made with regard to survival, changes in body weight and food intake, general conditions, hemoglobin concentration, red blood cell count and histopathologic changes.

The soybean oil emulsion was well tolerated by rats even at a dosage level of 6.0 gm. of fat per kg. of body weight per day. No rats of either group died during the thirty day fat injection period. In rats given 2.0 gm. of fat per kg. per day, the body weight and food intake were apparently normal, and no adverse effects of any type were observed. Lag in body weight gain and reduced food intake were observed during the fat-injection period in rats given 6.0 gm. of fat per kg. per day. Diarrhea and an increased incidence in respiratory tract infections were encountered and a moderate degree of anemia also developed.

A minute quantity of intravenous fat pigment was observed in the sections of the spleen of all rats. It was only occasionally found within the cytoplasm of a few of the Kupifer cells. In liver sections of some rats intravenous fat pigment was not detectable. There was no difference in the quantity of intravenous fat pigment in the liver and spleen between rats given 2.0 and 6.0 gm. of fat per kg. per day.