Lecture 14 - Hypolipidemic and Antianginal Drugs Flashcards
What medical conditions could result from vessel blockage?
- Coronary artery disease and heart attack
- Angina
- Stroke or transient ischemic attack
- Peripheral artery disease
- Intermittent claudication (pain and numbness in the limbs)
What is the physiological function of cholesterol?
- Building block of steroid hormones
- Essential for building cell membranes and myelin sheath
- Important for building signal domains
- Core component of bile salts secreted by the gallbladder to digest dietary fats
Source: 75-80% is synthesized in the liver and intestine, 20-25% via absorption
What are lipoproteins?
Apoproteins attached to cholesterol and fat
Types of lipoproteins
Chylomicrons
- Apoproteins B48 and triglycerides (90%)
- Transport dietary triglycerides and exogenous cholesterol
Types of lipoproteins
Very-low-density lipoprotein (VLDL)
- Apoproteins A1, B100, triglyceride (55%), and cholesterol (20%)
Types of lipoproteins
Low-density lipoprotein (LDL)
- Apoprotein B-100, cholesterol (53%)
Types of lipoproteins
High-density lipoprotein (HDL)
- Apoproteins E and cholesterol (20%)
Chylomicron processing pathway
- Lymph absorbs chylomicron from small intestine
- Lymph drains into bloodstream
- Lipoprotein lipase removes lipids from chylomicrons
- Lipids stored in adipocytes or used by other cells while liver disposes remnants of the chylomicron
VLDL/LDL processing pathway
- Liver produces VLDLs
- Triglycerides are removed and stored in adipocytes. VLDLs become LDLs containing mainly cholesterol
- cells absorb LDLs by receptor-mediated endocytosis
HDL processing pathway
- Liver produces empty HDL shells
- HDL shells pick up cholesterol and phospholipids from tissues
- Filled HDLs return to liver
- Liver excretes excess cholesterol and bile acids
How is plaque formed?
Plaque begins as streaks of fat in the arterial wall. When a vessel is damaged through infection, inflammation, diabetes, or high blood pressure, LDL-cholesterol migrates to the injured area. LDL is then consumed by macrophages
which transform into cholesterol-rich foam cells. Foam cell production continues over time and causes buildup of atherosclerotic plaque.
What is stable plaque?
Has a cholesterol core with fibrous cap and may contain calcium
What is unstable plaque?
Has a cholesterol core with a thin cap that can erode and rupture
Why is LDL cholesterol considered ‘bad cholesterol’?
LDL is atherogenic. It transports cholesterol to damaged areas in the arteries and forms plaques
Why is HDL cholesterol considered ‘good cholesterol’?
HDL is anti-atherogenic. it goes looking for cholesterol to return to the liver for disposal
What is lipidemia?
The presence of excess lipids in the blood
List the types of hypolipidemic drugs
1) HMG-CoA reductase inhibitors
(statins)
2) Bile acid sequestrants
3) Cholesterol absorption inhibitors
4) Fibric acid derivatives
5) Nicotinic acid (Vitamin B3, Niacin)
Statins - Clinical indications
- Treatment of primary hyperlipidemias
- To slow the progression of atherosclerosis
Statins - Mechanism of action
- Competitively inhibit HMG-CoA reductase (first commited reaction of cholesterol synthesis)
- Reduces plasma levels of LDL and cholesterol
- Decrease plasma levels of triglycerides
- Increase HDL-cholesterol levels
- Lower the levels of C-reactive protein
What is C-reactive protein?
A protein released during injury and inflammation. High levels may increase the risk for atherosclerosis.
List some statins
Simvastatin, Atorvastatin, Fluvastatin, Prevastatin, etc.
Statins - Contraindications
Pregnancy and breastfeeding
- cholesterol is an essential component for fetal and infant sythesis of steroids and cell membrane development
Statins - major side effects
Muscle weakness, myopathy (rare), and liver damage
Ezetimibe - Mechanism of action
Cholesterol absorption inhibitor
- Acts on the surface of the small intestine to selectively block the absorption of cholesterol
- Decreases VLDL and circulating LDL-cholesterol