Hyperlipidemias Flashcards
What are lipoproteins made of?
- Have a central core of lipids (triglycerides and cholesterol esters)
- An outer case of phospholipids, free cholesterol and proteins (called apoproteins)
What are the classes of lipoproteins?
(1) Chylomicrons
(2) VLDL
(3) IDL
(4) LDL
(5) HDL
- They all differ in size, density and relative proportion of the core lipids and type of apoproteins-
Hyperlipidemia
An increase in plasma lipids in general
Hypercholesterolemia
An increase in plasma cholesterol, indicated by an increases in LDL (familial, hypothyroidism, corticosteroids)
Hypertriglyceridemia or Hyperlipemia
An increase in triglycerides, indicated by an increase in VLDL (familial, diabetes, centripetal obesity, alcohol use, corticosteroids, estrogens)
Mixed hyperlipidemia
An increase in both cholesterol and triglycerides (LDL & VLDL)
What contributes to increased risk of coronary artery disease?
(1) High LDL cholesterol
(2) Low HDL cholesterol
(3) Hypertriglyceridemia (increased VLDL)
Which lipoproteins are rich in triglycerides? Cholesterol? Apoproteins?
VLDLs, LDL, HDLs respectively
Which lipoproteins are large/small in size?
Chylomicrons very large in size, VLDLs smaller in size than chylomicrons, HDLs very small in size,
What are desirable levels of Total Cholesterol and LDL Cholesterol? Borderline high? High?
(1) Desirable- 240, >160
What are the desirable LDL levels for moderate and high risk patients?
- Moderate risk: LDL <70
What are the 5 classes of Lipid-lowering drugs?
(1) HMG-CoA reductase inhibitors (Statins)
(2) Niacin (Nicotinic acid)
(3) Fibric acid derivatives
(4) Bile acid binding agents
(5) Inhibitors of intestinal sterol absorption
What do you have to make sure of with drugs that alter plasma lipoprotein concentrations?
They may require adjustment of warfarin doses
What are the HMG-CoA Reductase inhibitors?
(1) Lovastatin
(2) Atorvastatin
What drug is the most effective in reducing LDL?
Statins (HMG-CoA reductase inhibitors)
Lovastatin/Atorvastatin- Mechanism of Action
(1) Reduce cholesterol synthesis by inhibition of HMG Co A reductase
(2) Increases LDL receptors (indirect effect), thus increasing the extraction of LDL by the liver and decreasing LDL in the plasma
Statins- Uses
(1) Hypercholesterolemia (increased LDL)
(2) Mixed hyperlipidemia (LDL and VLDL increase)
(3) First line of treatment after M.I.
Statins- Adverse effects
(1) Hepatitis (increase of hepatic enzymes such as serum amino transferase)
(2) Myalgia
When should statins be discontinued?
If serum levels of creatine phosphokinase are elevated of if myopathy occurs (rhabdo, myoglobinuria)
Niacin- Mechanism of Action
(1) Reduces VLDL secretion from liver and in turn, decreases production of LDL
(2) Inhibits lipolysis in adipose tissue, decreasing FFA supply to the liver and VLDL synthesis
(3) Increases VLDL clearance in the plasma by increasing LPL activity
(4) Decreases catabolism of HDL and increases HDL
Niacin- Uses
(1) Useful in mixed hyperlipidemia because of its favorable effects of VLDL, LDL, and HDL
(2) combined with other drugs for hypercholesterolemia and hypertriglyceridemia
Niacin- Adverse Effects
- Useful only in large doses which produce vasodilation
(1) cause skin flushing
(2) pruritis (usually goes away within first few days) - increase in serum transaminase level, gastric distress, glucose intolerance, and hyperuricemia
- Avoid in liver disease, peptic ulcer, gout, diabetes
What is used with Niacin to reduce adverse effects?
Aspirin (the effects are mediated by prostaglandins)
What are the fibric acid derivatives?
Gemfibrozil and Fenofibrate
Fibric acid derivatives- Mechanism of Action
(1) Decrease triglycerides (VLDL) by stimulation of LPL (hypolysis of VLDL), promote the delivery of FFA to adipose tissue
(2) May decrease VLDL synthesis in the liver
Fibric acid derivatives- Uses
- Used primarily in hypertriglyceridemia (increase in VLDL)
- May be used in mixed hyperlipidemia
Fibric acid derivatives- Adverse Effects
(1) Allergic reactions, myalgia, blood cell deficiencies, hypokalemia, and an increase in serum aminotransferase
(2) Risk of myopathy increases when used with HMG-CoA reductase inhibitors
(3) Moderate increase risk in gallstones
(4) Contraindicated in hepatic or renal dysfunction
T/F Fibric acid derivatives increase effects of warfarin.
TRUE because of it’s binding to plasma proteins
What are the bile acid binding agents?
Colestipol, Cholestyramine
Bile acid binding agents- Mechanism of Action
(1) Bind bile acids and prevent their absorption which leads to synthesis of replacement bile acids from cholesterols in the liver
- to obtain more cholesterol for this purpose, the liver increases LDL receptors leading to increased uptake of LDL from the plasma (indirect effect)
(2) May increase triglycerides and cause a small increase in HDL
Bile acid binding agents- Uses
(1) Hypercholesterolemia (moderately effective)(2) Used in patients who cannot tolerate other drugs or is used in combination with other drugs
Bile acid binding agents- Undesirable effects
- annoyoing GI effects (nausea, abdominal bloating, constipation), limit their widespread use
- interfere with absorption of fat-soluble vitamins and drugs such as digoxin, hydrocholothiazide, and warfarin
T/F Bile acid binding agents are absorbed, leading to systemic adverse effects.
FALSE; they are not absorbed, no systemic adverse effects
What does Ezetimibe do?
inhibits intestinal absorption of cholesterol and phytosterols
Ezetimibe- mechanism of action
- effective even in the absence of dietary cholesterol because it inhibits the absorption of cholesterol excreted in the bile
- decreased delivery of intestinal cholesterol to the liver by chylomicron remnants stimulates expression of hepatic LDL receptor, thus enhancing clearance of LDL from the plasma (cholesterol synthesis is increased, however)
Does Ezetimibe has a high or low incidence of toxicity?
Low (reversible impaired hepatic function)
What are the indications of combined drug therapy?
When LDL levels are not normalized with a single agent or when LDL and VLDL levels are both elevated
What is the effectiveness of combined drug therapy?
- Statins alone decrease LDL cholesterol by 25-45%. Addition of bild acid binding resins can produce a further decrease in LDL cholesterol by 20-25%, whereas addition of nicotinic acid can produce an additional decrease of 15-20%
- All three drugs combined can produce decreases in LDL cholesterol up to 70%
What is Vytorin? Is it more effective than single drug therapy?
A combination tablet of ezetimibe and simvastatin that is approved for use; several studies show that Vytorin is no more effective than a statin at reducing heart attack risk and may increase cancer risk
What is Advicor and Simcor?
- Advicor- extended release niacin plus lovastatin
- Simcor: extended release niacin plus simvastatin
What is Lovaza?
Omega 3-acid ethyl esters
What does Lovasa do?
- Lowers very high TGs
- may reduce synthesis of TGs in the liver because EPA and DHA are poor substrates for the enzymes responsible for TG synthesis, and EPA and DHA inhibit esterification of other fatty acids
- Has been found to increase LDL levels in some patients
Lovasa- side effects
flu symptoms, infections, upset stomach and change in sense of taste
In what is Lovasa found?
in plants and the oil of fish (salmon and mackerel)