About Gemfibrozil Fibric Acid Derivative, Antilipemic agent. Mechanism of Action of Gemfibrozil The drug lowers circulating triglyceride levels by activating lipoprotein lipase which is a key enzyme in the degradation of VLDL (very low density lipoprotein) cholesterol. This effect is exerted through paroxisome proliferator-activated receptor alpha (PPARalpha) which enhances lipoprotein lipase synthesis and fatty acid oxidation. It also reduces hepatic triglyceride synthesis. It also reduces VLDL secretion by liver and increases HDL (high density lipoprotein) cholesterol. The increase in HDL cholesterol is partly due to transfer of surface lipid components from catabolised VLDL to HDL and also due to increased production of HDL apoproteins by liver. The small dense LDL have been shifted to larger less dense particles. It is highly effective in type III hyperlipoproteinemia and lowers raised blood cholesterol.