Week 5 - Cholesterol

Question 1

What are the types of lipid-lowering drugs?

Answer 1

• Statins - HMG-CoA reductase inhibitor
• Fibrates
• Bile acid binding resins
• Fish oil derivatives

Question 2

What are the actions of Very Low Density Lipoprotein (VLDL)?

Answer 2

-transport C and TG to tissues where TG is removed

Question 3

What are the actions of Low Density Lipoprotein (LDL)?

Answer 3

• large component of C
• -some taken up by tissues and liver
• endocytosis via specific LDL receptors

Question 4

What are the actions of High Density Lipoprotein (HDL)?

Answer 4

• absorb C from cell breakdown in tissues

- transfer C to VLDL and LDL

Question 5

What are the types of lipid-lowering drugs?

Answer 5

• Statins - HMG-CoA reductase inhibitor
• Fibrates
• Bile acid binding resins
• Fish oil derivatives

Question 6

What is the characteristics of HMG-CoA reductase?

Answer 6

• the rate limiting step in biosynthesis of cholesterol

- blocks conversion of HMG-CoA to mevalonic acid

Question 7

What are the actions and effects of Lovostatin?

Answer 7

• reversible competetive inhibitor of HMG enzyme
• decrease hepatic cholesterol synthesis
• increasing synthesis of LDL receptors
• increasing clearance of LDL
• reducing plasma LDL [ ]

Question 8

How are lipids (cholesterol (C) and triglycerides (TG)) transported?

Answer 8

in the plasma as lipoproteins

Question 9

What are the actions of Chylomicrons?

Answer 9

• transport TG and C from GIT to tissues
• lipoprotein lipase release the free fatty acids (FFA)
• taken up by muscle and adipose tissue;
• chylomicron remnants taken up in liver,
• C is stored and oxidised to bile acids or released

Question 10

What are some other actions of Statins?

Answer 10

• improve endothelial function (NO)
• reduced vascular inflammation
• reduced platelet aggregation
• increased vascularisation of ischemic tissue
• stabilisation of plaque
• antithrombotic actions
• enhanced fibrinolysis
• immune suppression

Question 11

What are examples of Fibrates?

Answer 11

• fenfibrate, gemfibrozil

Question 12

What are the action of Fibrates?

Answer 12

Cause a reduction in plasma VLDL levels

-thus triglycerides

Question 13

What are the uses of Fibrates?

Answer 13

hyperlipoproteinaemias

Question 14

What are the mechanisms of Fibrates?

Answer 14

• inhibits receptors that stimulate fatty acid oxidation
• stimulate lipoprotein lipase
• increase TG and VLDL hydrolysis
• storage in fat or use as fuel

Question 15

What are the mechanisms of Fibrates?

Answer 15

• inhibits receptors that stimulate fatty acid oxidation
• stimulate lipoprotein lipase
• increase TG and VLDL hydrolysis
• storage in fat or use as fuel

Question 16

What are examples of Bile acid binding resins?

Answer 16

colestyramine

Question 17

What are the action of Bile acid binding resins?

Answer 17

• rate of excretion of C increased
• increase rate of LDL receptors made
• increased clearance of LDL

Question 18

What are the uses of Bile acid binding resins?

Answer 18

-Used with statin to increase efficacy of LDL reduction

Question 19

What are the mechanisms of Bile acid binding resins?

Answer 19

• anion exchange resins
• sequester bile acids in intestine preventing reabsorption
• decreased enterohepatic recirculation
• -resin not absorbed

Question 20

What are the characterisitics of Bile Acids? and the reason bile acid binding resins are used

Answer 20

• synthesised in liver from cholesterol
• stored in gall bladder, secreted into duodenum
• used in digestion of lipids
• keep more bile in gut -> body has to make more -> uses more cholesterol