Hypolipidemic agent

Hypolipidemic agents, or antihyperlipidemic agents, are a diverse group of pharmaceuticals that are used in the treatment of hyperlipidemias. They are called lipid-lowering drugs (LLD) or agents.

Classes of hypolipidemic drugs

There are several classes of hypolipidemic drugs. They may differ in both their impact on the cholesterol profile and adverse effects. For example, some may lower the "bad cholesterol" low density lipoprotein (LDL) more so than others, while others may preferentially increase high density lipoprotein (HDL), "the good cholesterol". Clinically, the choice of an agent will depend on the patient's cholesterol profile, cardiovascular risk, and the liver and kidney functions of the patient, evaluated against the balancing of risks and benefits of the medications. In the United States, this is guided by the evidence-based guideline from the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATPIII).

Established

• statins are particularly well-suited for lowering LDL, the cholesterol with the strongest links to cardiovascular diseases. In studies using standard doses, statins have been found to lower LDL-C by 18% to 55%, depending on the specific statin being used. There is a risk of severe muscle damage (myopathy & rhabdomyolysis) with statins.
• fibrates are indicated for hypertriglyceridemia. Fibrates typically lower triglycerides by 20% to 50%. Level of the good cholesterol HDL is also increased. Fibrates may decrease LDL, though generally to a lesser degree than statins. Similar to statins, there is a risk of severe muscle damage (myopathy & rhabdomyolysis) with fibrates.
• niacin, like fibrates, is also well-suited for lowering triglycerides by 20-50%. It may also lower LDL by 5-25% and increase HDL by 15-35%. Niacin may cause hyperglycemia, and may also cause liver damage. The niacin derivative acipimox is also associated with a modest decrease in LDL.
• bile acid sequestrants (resins) are particularly effective for lowering LDL-C by sequestering the cholesterol-containing bile acids released into the intestine and preventing their reabsorption from the intestine. It decreases LDL by 15-30% and raises HDL by 3-5%. It has little effect on triglycerides but can cause a slight increase. Bile acid sequestrants may cause gastrointestinal problems, and may also reduce the absorption of other drugs and vitamins from the gut.
• ezetimibe (Zetia) is a selective inhibitor of dietary cholesterol absorption.
• phytosterols may be found naturally in plants. Similar to ezetimibe, phytosterols reduce the absorption of cholesterol in the gut. Hence, they are most effective when consumed with meals. However, the precise mechanism of action of phytosterols differs from ezetimibe.
• Orlistat (Xenical): Its primary function is to prevent the absorption of about 30%of fats from the human diet; thereby reducing caloric intake (a drug designed to treat obesity) is by inhibiting Pancreatic lipase- an enzyme that breaks down triglycerides in the intestine.

Investigational

Investigational classes of hypolipidemic agents:

• CETP Inhibitors (cholesteryl ester transfer protein inhibitors) are still under development. It is expected that these drugs will mainly increase HDL while lowering LDL.
• squalene synthase inhibitor
• ApoA-1 Milano
• AGI-1067
• mipomersen (completed 4 phase III trials - may file NDA in 2011)

See also

• ATC code C10