The effect of phenobarbital on human plasma lipids

The effect of phenobarbital to increase the activity of hepatic microsomal enzyme system, resulting in an increase in high density lipoprotein (HDL)-cholesterol, is well known. However, it remains uncertain whether phenobarbital increases plasma concentrations of cholesterol and triglyceride, and which subfractions of the high density lipoprotein fractions phenobarbital increases. The present study was therefore, conducted to investigate these points. Long-term treatment of phenobarbital increased the plasma concentrations of HDL2-cholesterol, HDL3-cholesterol and HDL3-phospholipid, and decreased the plasma concentrations of low density lipoprotein + very low density lipoprotein-cholesterol. On the other hand, its long-term treatment did not affect the plasma concentrations of cholesterol, triglyceride and phospholipid. In addition, phenobarbital increased the plasma concentration of apolipoprotein A-I, decreased the plasma concentration of apolipoprotein B, but did not affect the plasma concentration of apolipoprotein A-II. These results indicate the possibility that phenobarbital has an antiatherogenic effect.