Hyperlipidemia refers to elevated plasma lipid levels, usually in the form of lipoproteins containing a hydrophobic lipid core enclosed by a hydrophilic coat. Lipid-lowering drugs act by reducing lipoprotein production or increasing their removal from blood to decrease plasma cholesterol levels. These drugs include HMG-CoA reductase inhibitors (statins), fibric acid derivatives, bile acid sequestrants, LDL oxidation inhibitors, and miscellaneous agents such as nicotinic acid. Statins are the most potent class and work by competitively inhibiting HMG-CoA reductase to reduce intracellular cholesterol levels and increase LDL receptor expression and clearance of LDL from blood.