Effects of various hypolipidemic drugs on fatty acid composition of liver and serum lipids.

1. Treatment of rats with hypolipidemic drugs elicited an increase in oleic and a decrease in linoleic acid content in cholesterol esters, triglycerides and phospholipids of serum and liver lipids. 2. The change was most pronounced in triglycerides followed by cholesterol esters and phospholipids. 3. The shift was dose-dependent, starting with doses eliciting hypolipidemic effects. 4. The shift became obvious immediately after beginning of treatment and reached after 4 days a new steady state. 5. This effect was shared by both drugs of aryloxy fatty acid structure, but was not seen with either L-thyroxine or nicotinic acid. 6. The mechanism underlying this phenomenon is thus far unknown, but in our view it merits further attention.