Gemfibrozil - sold under brand name of Lopid, Jezil and others - is used to treat abnormal blood lipid levels. Currently around 4 million prescriptions per year in the US alone. Its mechanism of action is, to date, unknown.

The exact mechanism of action of gemfibrozil is unknown; however, several theories exist regarding the very low density lipoprotein (VLDL) effect; it can inhibit lipolysis and decrease subsequent hepatic fatty acid uptake as well as inhibit hepatic secretion of VLDL; together these actions decrease serum VLDL levels and increase HDL-cholesterol; the mechanism behind HDL elevation is currently unknown.

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