Pharmacology 17 - Atherosclerosis and Lipid Metabolism Flashcards
1
Q
Describe the exogenous pathway of lipid metabolism
A
- Dietary triglycerides and cholesterol to a chylomicron (SI)
- LP lipase converts this to free fatty acids and chylomicron remnant
- Mostly taken to the liver, however there is some formation of atheroma
- Some lipids end up in skeletal muscle and some in adipose tissue
2
Q
Describe the stages of endothelial dysfunction in atherosclerosis
A
- Increased endothelial permeability
- Upregulation of endothelial adhesion molecules
- Leukocyte adhesion
- Migration of leukocytes into the artery wall
3
Q
Describe fatty streak formation in atherosclerosis
A
- Adherance and entry of leukocytes
- Migration of smooth muscle cells
- Activation of T cells
- Adherence and aggregation of platelets
- Formation of foam cells
4
Q
Describe formation of the atherosclerotic plaque
A
- Formation of fibrous cap (becomes more complicated)
- Accumulation of macrophages
- Formation of necrotic core (macrophages die)
5
Q
List the risks of LDL cholesterol
A
- Strongly associated with atherosclerosis and CHD events
- 10% increase results in 20% increase in CHD risk
- Modified by smoking, hypertension, diabetes and low HDL (these factors enhance the problem)
6
Q
What is HDL cholesterol?
A
- Protective effect for the risk of atherosclerosis and CHD
- Lower level, higher risk of atherosclerosis
- Levels are lower when triglycerides are high
- Lowered by smoking, obesity and physical inactivity
7
Q
How do statins work?
A
- Inhibit HMG-coA reductase, preventing conversion of HMG-CoA to mevalonic acid
- Prevents cholesterol production, reduces the number of LDL particles, by increasing the number of LDL receptors expressed on hepatocytes
8
Q
How do fibrates work?
A
- Activate PPAR alpha receptors (peroxisome proliferator activated receptors)
- Increases HDL (effective)
- Reduces triglycerides and fatty acids in the plasma
- Increases cellular uptake of adipose tissue
9
Q
How does ezetimibe work?
A
- Inhibits cholesterol absorption in the intestine
- Absorbed and then activated as glucaronide
- 15-20% reduction in LDL cholesterol. Used in conjunction with statins to further reduce cholesterol (due to rule of 6).
10
Q
Describe the endogenous pathway of lipid metabolism
**
A
- Liver makes VLDL. In the blood, VLDL is converted to IDL and LDL. The liver contains IDL and LDL receptors, so will reuptake cholesterol and excrete into the GIT in bile
- HDL can be broken down by cholesteryl ester transfer protein (CeTP) into LDL and VLDL in the periphery. This is reverse cholesterol transport
11
Q
How is inflammation important in atherosclerosis?
A
- Leaky capillary walls causes monocytes to enter the vessel wall
- Begins with the defective endothelium
12
Q
What are remnant lipids?
A
- Formed by partial breakdown of chylomicrons and large lipid molecules
- Atherogenic
13
Q
What is atherosclerosis?
A
- Inflammatory fibroproliferative disease primarily
- Not always inflammatory however
14
Q
Compare stable and vulnerable atherosclerotic plaques
A
- Stable have a thick wall (usually collagen) which divides the lumen from the lipid core, although the lumen is very narrow. Often angina symptoms but a good prognosis
- Unstable (vulnerable plaques) have a large lumen but a thin division between the lipid core and lumen, which could break down following high blood pressure of inflammation. Can result in thrombus formation by activation of coagulation.
15
Q
List the drug therapies for cholesterol
A
- Bile acid sequestrants (decrease absorption of LDL, increase HDL. Poorly tolerated.)
- Nicotinic acid (Decreases LDL, TC, increases HDL, decreases TG. Poor tolerability)
- Fibrates - gemfibrozil (decreases TC, LDL, increased HDL, decreases TG. Good tolerability)
- Statins (decrease TC, LDL, TG increase HDL. Good tolerability)
- Ezetimibe (TC, LDL, TG down and HDL up, good tolerability)
