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Medicine Year 1 - Semester 2 - Part 1 > Cholesterol Lowering Drugs > Flashcards

Cholesterol Lowering Drugs Flashcards

1
Q

Describe the structure of lipoproteins

A

Central core of hydrophobic lipid

Hydrophilic coat of polar substances

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2
Q

Hydrophobic lipids

A

Triglycerides or Cholesterol esters

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3
Q

Hydrophilic coat of substances

A

Phospholipids
Free Cholesterol
Associated proteins

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4
Q

State the 5 main classes of lipoproteins

A

High density lipoproteins
Intermediate density lipoproteins
Low density lipoproteins
Very Low density lipoproteins
Chylomicrons

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5
Q

Describe chylomicrons

A

Massive, huge diameter lipoproteins, thus storing fatty acids and cholesterol from the diet.

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6
Q

How do the 5 main classes of lipoproteins vary ?

A

Vary in :

  • Size
  • Density
  • Apoproteins
  • Core lipids
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7
Q

State the 2 pathways for cholesterol synthesis

A

Endogenous pathway
Exogenous pathway

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8
Q

Exogenous pathway

A

External source of cholesterol

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9
Q

Endogenous pathway

A

Internal ability of the body to produce a source of cholesterol

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10
Q

Function of chylomicrons

A

Transport tri-acylglycerides and cholesterol esters from the GI to the tissues.

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11
Q

Function of lipoprotein lipase

A

Chylomicrons are split by lipoprotein lipase to release free fatty acids.

These free fatty acids are taken up by muscle and adipose tissue

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12
Q

What happens to chylomicrons after interacting with lipoprotein lipase ?

A

The cholesterol enriched, fatty acid depleted chylomicron (chylomicron remnant) is taken up in the liver.

The cholesterol is stored and oxidised into bile acids or released to VLDL.

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13
Q

Function of VLDL (very low density lipoprotein)

A

Transports cholesterol and newly synthesised tri-acylglycerols to the tissues.

TGs removed from VLDL leaving LDL with a high cholesterol.

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14
Q

Function of HDL

A

Absorbs cholesterol from cell breakdown and transfers it to VLDL.

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15
Q

Requirements for endogenous creation of cholesterol

A

A source of acetyl-CoA
A source of enzymes

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16
Q

What does regulation of the endogenous pathway depend on ?

A

Based on how much cholesterol you already have in your body.

XS cholesterol - you don’t need to synthesise as much endogenous cholesterol

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17
Q

What is synthesised from cholesterol ?

A

Bile acids

(important for GI function of the body)

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18
Q

What happens if we have elevated plasma cholesterol ?

A

Elevated plasma cholesterol is associated with high LDL which is a risk factor for ATHEROMATOUS DISEASE.

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19
Q

What does atheromatous disease lead to ?

A

Atherosclerosis
Ischaemic Heart disease
Myocardial infarction
Cerebral Vascular Accidents

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20
Q

Hyperlipidaemia

A

An increase in plasma concentration of lipids

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21
Q

What causes an increased risk of atherosclerosis and CHD ?

A

High plasma conc. of total and LDL cholesterol.

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22
Q

State the average total cholesterol level in the UK

A

5.7 mmol/L

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23
Q

State the ideal levels of cholesterol

A

<5 mmol/L

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24
Q

State the mildly high levels of cholesterol

A

5 - 6.4 mmol/L

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25
Q

State the moderately high levels of cholesterol

A

6.5 - 7.8 mmol/L

26
Q

State the very high levels of cholesterol

A

> 7.8 mmol/L

27
Q

When considering high cholesterol, what other factors have to be taken into account ?

A

The ratio between ‘good’ HDL and ‘bad’ LDL cholesterol.

Other risk factors for CVD

28
Q

Where is cholesterol derived from ?

A

De novo synthesis in the liver
Uptake from circulating LDLs
Uptake of chylomicron remnants

29
Q

What is the aim of lipid lowering drugs ?

A

Reduce plasma cholesterol

  • lifestyle modification
  • drug therapy should be secondary
30
Q

Describe how lipid lowering drugs work

A

Work by either reducing production of lipoproteins

OR

Increasing their removal from the blood

31
Q

State the drugs that are used to lower blood cholesterol levels

A

Bile Acid sequestrants
PCSK9 inhibitors
Ezetimibe
Fibrates
Statins , Bempedoic acid

32
Q

State the mechanism of action of Bile Acid sequestrants

A

Sequester bile acids in the intestine / decrease hepatic stores of cholesterol.

33
Q

State the mechanism of action of PCSK9 inhibitors

A

Enhances the removal of LDL

34
Q

State the mechanism of action of ezetimibe

A

Inhibits transport protein for cholesterol in the brush border of enterocytes in the duodenum

35
Q

State the mechanism of action of fibrates

A

Alter the levels of plasma lipoproteins

36
Q

State the mechanism of action of statins, bempedoic acid

A

Inhibit the synthesis of cholesterol in the liver

37
Q

What are statins ?

A

HMG-CoA reductase inhibitors

38
Q

Function of HMG-CoA reductase

A

Major rate limiting step in cholesterol synthesis.

Converts HMG-CoA to mevalonic acid (MVA)

39
Q

State some examples of statin

A

Atorvastatin
Simvastatin
Pravastatin
Rosuvastatin

These are all long-lasting HMG-CoA reductase inhibitors.

40
Q

Describe the steps in the mevalonate pathway

A

One Half - Cholesterol synthesis
Other Half - Protein Prenylation

41
Q

What is protein prenylation ?

A

Addition of lipid tails to small GTPase signalling molecules

Ensures they are localised correctly.

42
Q

Lipoprotein lipases function

A

An enzyme that helps remove and strip fatty acids from lipoproteins

43
Q

Clinical uses of statins

A

2ndary prevention of myocardial infarction and stroke in those who have atherosclerotic diseases.

1ary prevention of arterial diseases in patients with high serum cholesterol.

44
Q

Function of atorvastatin

A

Lowers serum cholesterol in familial hypercholesterolaemia.

45
Q

What to use if statins don’t work ?

A

Ezetimibe
PCSK9 inhibitors
Bempedoic Acid

46
Q

Function of ezetimibe

A

Specifically reduces intestinal cholesterol absorption by inhibiting a sterol carrier protein in the brush border of the enterocytes.

Inhibits uptake of cholesterol

47
Q

Function of PCSK9 inhibitors

A

PCSK9 mediates the degradation of LDL receptors on the surface of liver cells, inhibiting this enzyme increases the amount of LDL bound and removed by the liver.

48
Q

State some PCSK9 Inhibitors

A

Antibodies :

Alirocumab
Evolcumab

49
Q

Function of bempedoic acid

A

Reduces cholesterol synthesis in the liver by inhibiting ATP citrate lyase.

50
Q

Lipid targeting treatments

A

Colestyramine
Fibrates

51
Q

What is colestyramine ?

A

Basic anion exchange resin

52
Q

Describe the action of colestyramine

A

Sequesters bile acids to prevent enterohepatic recirculation.

Increases the metabolism of endogenous cholesterol into bile acids

Increases the LDL receptor numbers in the liver resulting in the removal of LDLs from the blood.

53
Q

Function of bile-sequestering drugs

A

Bile sequestering drugs and inhibitors of cholesterol biosynthesis can lower blood cholesterol by 50%.

54
Q

What are fibrates ?

A

Activators of lipoprotein lipase

55
Q

State some fibrates

A

Fenofibrate
Gemfibrozol

56
Q

Main action of fibrates

A

Stimulation of lipoprotein lipase which decreases the triglyceride concentration of VLDL.

57
Q

What are the clinical uses of fibrates ?

A

Patients with :

  • Diabetes
  • Mixed dyslipidaemia
  • Elevated LDL cholesterol
  • high cardiovascular risk
  • marker hypertriglceridaemia
  • low HDL cholesterol
58
Q

Side effects of statins

A

Myositis
Angio-oedema
GI disturbances
Insomnia
Rash

(not used in pregnancy)

59
Q

Side effects of bempedoic acid

A

Anaemia
Gout
Hyperuricaemia

60
Q

Side effects of PCSK9 inhibitors

A

Flu-like symptoms
Muscle pain

61
Q

Side effects of Fibrates

A

Myositis
GI disturbances

62
Q

Side effects of colestyramine and ezetimibe

A

GI symptoms
Nausea
Abdominal Bloating
Constipation
Diarrhoea

Medicine Year 1 - Semester 2 - Part 1 (51 decks)

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