Gemfibrozil, sold under the brand name Lopid among others, is a medication used to treat abnormal blood lipid levels. It is generally less preferred than statins. Use is recommended together with dietary changes and exercise. It is unclear if it changes the risk of heart disease. It is taken by mouth. Common side effects include headache, dizziness, feeling tired, and intestinal upset. Serious side effects may include angioedema, gallstones, liver problems, and muscle breakdown. Use in pregnancy and breastfeeding is of unclear safety. It belongs to the fibrates group of medications and works by decreasing the breakdown of lipids in fat cells. Gemfibrozil was patented in 1968 and came into medical use in 1982. It is available as a generic medication. In 2020, it was the 189th most commonly prescribed medication in the United States, with more than 2million prescriptions. Medical uses Hyperlipidemia (Type III) Hypertriglyceridemia (Type IV): Gemfibrozil, though not as effective as niacin (nicotinic acid, a form of Vitamin B3), is better tolerated. Reduce triglyceride levels Reduce very low density lipoprotein (VLDL) levels Modest reduction of low density lipoprotein (LDL) levels Moderate increase in high density lipoprotein (HDL) levels Side effects GI distress Musculoskeletal pain Increased incidence of gallstone Hypokalemia (low blood potassium) Increased risk of cancer Contraindications Gemfibrozil should not be given to these patients: Hepatic dysfunction Gemfibrozil should be used with caution in these higher risk categories: Biliary tract disease Renal dysfunction Pregnant women Obese patients Drug interactions Anticoagulants: Gemfibrozil potentiates the action of warfarin and indanedione anticoagulants. Statin drugs: Concomitant administration of fibrates (including gemfibrozil) with statin drugs increases the risk of muscle cramping, myopathy, and rhabdomyolysis. Gemfibrozil inhibits the activation of the liver's Cytochrome P450 system and CYP2C8, reducing hepatic metabolism of many drugs, and prolonging their half lives and duration of action. Drugs metabolized by the Cytochrome P450 system include: Many antidepressants Many antipsychotics Many antiepileptics Theophylline and other methylxanthine drugs Several anesthetic agents Oral contraceptive pills Statins Warfarin Selexipag Mechanism of actions 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. Gemfibrozil increases the activity of extrahepatic lipoprotein lipase (LL), thereby increasing lipoprotein