Lipid Lowering Drugs Overview

Lipid Lowering Drugs (Antilipemic Drugs)

• Lipid lowering drugs, also known as antilipemic drugs, are used to manage plasma lipid levels.
• Lipoproteins are combinations of lipids and proteins that transport lipids in the blood.
• Triglycerides (TGs) and cholesterol are the primary forms of lipids in the blood.
• These lipids are water-insoluble and must be packaged for transport in the blood.
• Lipoproteins have a hydrophilic shell composed of phospholipids and carry a hydrophobic core of cholesterol and triglycerides.

Lipoprotein Types

• Chylomicrons: Produced in the gastrointestinal (GI) tract.
• Very-low-density lipoprotein (VLDL): Produced by the liver, transports triglycerides to cells.
• Low-density lipoprotein (LDL): Often called "bad" cholesterol due to its role in plaque formation in arteries; rich in cholesterol, essential for cell membranes and steroid hormones.
• High-density lipoprotein (HDL): Often called "good" cholesterol; responsible for cholesterol recycling, which benefits the body.

Coronary Artery Disease

• Non-modifiable factors for CAD include:
  • Age (Males ≥ 45, Females ≥55 or postmenopausal)
  • Strong family history of premature Coronary Artery Disease.
• Modifiable factors for CAD include:
  • Current cigarette smoker
  • Abdominal obesity
  • Hypertension (BP ≥ 140/90 or on antihypertensive medication)
  • Diabetes Mellitus
  • Low-density lipoprotein/high-density lipoprotein ratio

Lipid Lowering Drug Groups and Mechanisms

• HMG-CoA reductase inhibitors (statins): These drugs inhibit the enzyme HMG-CoA reductase, an important liver enzyme responsible for cholesterol production. This lowers the rate of cholesterol production in the liver. By inhibiting HMG-CoA reductase, the liver produces more LDL receptors. This increases plasma clearance of LDL. This class of drugs also decreases VLDL and increases HDL.
  • Examples include atorvastatin (Lipitor), rosuvastatin (Crestor), lovastatin (Mevacor), and simvastatin (Zocor). Rosuvastatin has demonstrated possibly less adverse effects in some clinical trials and lower doses might be utilized in Asian patients.
• Inhibitors of Cholesterol Absorption
• Niacin (nicotinic acid)
• Fibric acid derivatives

HMG-CoA Reductase Inhibitors: Mechanism of Action

• Inhibit HMG-CoA reductase, a vital liver enzyme involved in cholesterol synthesis.
• This action lowers the rate of cholesterol production.

HMG-CoA Reductase Inhibitors: Indications

• First-line therapy for hypercholesterolemia.
• Treatment for hyperlipidemias type IIa and IIb
• High LDL cholesterol levels.

HMG-CoA Reductase Inhibitors: Adverse Effects

• Mild, transient gastrointestinal (GI) disturbances, such as headache.
• Muscle pain (myalgia), and in rare cases, rhabdomyolysis (muscle breakdown).
• Liver injury (elevation of liver enzymes). Care is needed with patients with pre-existing liver dysfunction such as viral hepatitis.
• Statins are not used during pregnancy.

Considerations with Statins

• Asian patients may benefit from lower doses of specific statins. Rosuvastatin might be a preferred choice among this group.
• Grapefruit and grapefruit juice can inhibit CYP3A4, an enzyme involved in metabolizing some statins, and can lead to increased levels of statins in the blood, possibly having serious effects on anticoagulant users.
• Drug interactions with statins can occur with inhibitors of CYP3A4, such as warfarin (oral anticoagulant), erythromycin (macrolide antibiotic), and ritonavir (HIV protease inhibitor).

This quiz covers key concepts related to lipid lowering drugs, also known as antilipemic drugs, and their role in managing plasma lipid levels. It discusses different types of lipoproteins, their functions, and significance in lipid transport and health. Test your knowledge on chylomicrons, VLDL, LDL, and HDL.