Hypolipidemic Drugs (Antihyperlipidemic Drugs), Lipid Lowering Agents : Definition, Classification, Mechanism of action, Uses, Side Effects, Contraindications, & Interactions
Definition
- Hypolipidemic drugs are agents which lower the levels of lipids and lipoproteins in blood.
Classification
1. HMG Co-A reductase inhibitors (Statins)
- They are the most efficacious and best tolerated hypolipidaemic drugs.
- Because HMG-CoA reductase activity is maximum at midnight, all statins are administered at bed time to obtain maximum effectiveness. However, this is not necessary for atorvastatin and rosuvastatin, which have long plasma t 1/2.
Mechanism of action
- They competitively inhibit conversion of 3-Hydroxy-3-methyl glutaryl coenzyme A (HMG-CoA) to mevalonate (rate limiting step in CH synthesis) by the enzyme HMG-CoA reductase.
Effect on lipids (%)
- LDL ↓ (20-55)
- HDL ↑ (5-15)
- TG ↓ (10-35)
E.g.
- Atorvastatin
- Fluvastatin
- Lovastatin
- Pitavastatin
- Pravastatin
- Rosuvastatin
- Simvastatin
Uses
Statins are the first choice drugs for
- Primary hyperlipidaemias with raised LDL and total CH levels, with or without raised TG levels (Type Ila, IIb, V).
- Secondary (diabetes, nephrotic syndrome) hypercholesterolaemia.
2. Cholesterol absorption inhibitors
Mechanism of action
- Inhibits intestinal absorption of cholesterol and phytosterols. It interferes with a specific CH transport protein NPC1C1 in the intestinal mucosa and reduces absorption of both dietary and biliary CH.
E.g.
- Ezetimibe
3. Fibrates (Lipase)
Mechanism of action
- ↑ Activity of lipoprotein lipase
- ↓ release of fatty acids from adipose tissue
Effect on lipids
- LDL ↓ (However, may ↑ LDL when TG is high)
- HDL ↑
- TG ↓
E.g.
- Gemfibrozil
- Fenofibrate
- Clofibrate
- Bezafibrate
4. Bile acid sequestrants (Resins)
Mechanism of action
- ↓ bile acid absorption
- ↑ hepatic conversion of CH to bile acids
- ↑ LDL receptors on hepatocytes
Effect on lipids
- LDL ↓
- HDL ↑
- TG not affected, may ↑ in some
E.g.
- Colesevelam
- Colestipol
- Cholestyramine
5. Omega-3 fatty acids
E.g.
- Docosahexaenoic acid
- Eicosapentaenoic acid
- Icosapent ethyl
6. Niacin (Nicotinic acid)
Mechanism of action
- ↓ production of VLDL
- ↓ lipolysis in adipocytes
Effect on lipids
- LDL ↓
- HDL ↑
- TG ↓
7. Gugulipid
