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Pharmacology Chapter 29 Antilipemic Drugs

A drug that reduces lipid levels.
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Triglycerides and Cholesterol
- Two primary forms of lipids in the blood
- Triglycerides function as energy source and are stored in adipose tissue.
- Cholesterol is primarily used to make steroids hormones, cell membranes.and bile acids.

- Water-insoluble fats that must be bound to apolipoproteins, specialized lipid-carrying proteins
- Lipoprotein is the combination of triglyceride or cholesterol with apolipoprotein
Lipoproteins
Lipoprotein is the combination of triglyceride or cholesterol with apolipoprotein

- Lipoproteins transport lipids via the blood.

Different types:
- Very-low-density lipoprotein (VLDL)
Produced by the liver
Transports endogenous lipids to the cells

- Low-density lipoprotein (LDL)

- High-density lipoprotein (HDL)
Responsible for "recycling" of cholesterol
Also known as "good cholesterol"
Cholesterol levels and risk for CHD ( coronary heart disease)
The risk of CHD in patients with cholesterol levels of 300 mg/dL is three to four times greater than that in patients with levels less than 200 mg/dL
Coronary Heart Disease
Positive Risk Factors
-Age
Male 45 years or older
Female 55 years or older
Family history of premature CHD
- Current cigarette smoker

- Hypertension
BP 140/90 or higher, or on antihypertensive medication
- Low HDL levels: less than 40 mg/dL
-Diabetes mellitus
Coronary Heart Disease
Negative (Beneficial) Risk Factor
High HDL ("good" cholesterol): 60 mg/dL or higher
Treatment Guidelines
-Antilipemic drugs
Drugs used to lower lipid levels
Used as an adjunct to diet therapy
-Drug choice based on the specific lipid profile of the patient
- All reasonable non-drug means of controlling blood cholesterol levels (e.g., diet, exercise) should be tried for at least 6 months and found to fail before drug therapy is considered
The different types of antilipemic drugs
-HMG-CoA reductase inhibitors (HMGs, or statins)
-Bile acid sequestrants
-Niacin (nicotinic acid)
-Fibric acid derivatives (fibrates)
-Cholesterol absorption inhibitor (Zetia)
Combination drugs (Vytorin)
HMG-CoA Reductase Inhibitors (HMGs, or statins)
Most potent LDL reducers
HMG-CoA Reductase Inhibitors:
Mechanism of Action
-Inhibit HMG-CoA reductase, which is used by the liver to produce cholesterol
-LOWER RATE OF CHOLESTEROL PRODUCTION
HMG-CoA Reductase Inhibitors:
Indications
-First-line drug therapy for hypercholesterolemia
- Treatment of types IIa and IIb hyperlipidemias
Reduces LDL levels by 30% to 40%
Increases HDL levels by 2% to 15%
Reduces triglycerides by 10% to 30%
- Atorvastatin appears to be more effective in lowering triglyceride levels than other HMG-CoA reductase inhibitors.
HMG-CoA Reductase Inhibitors:
Adverse Effects & contraindications
Contraindications: allergy, pregnancy, liver disease or elevation in liver enzymes

Adverse Effects:
- Mild, transient GI disturbances, Rash and Headache. ( most common problems)
- Myopathy (muscle pain), possibly leading to the serious condition rhabdomyolysis
- Elevations in liver enzymes or liver disease
rhabdomyolysis
breakdown of muscle protein accompanied by myoglobinuria
- abnormal urinary excretion of protein can place a severe strain on the kidneys, possibly leading to acute renal failure and even death.
Atorvastatin (Lipitor)

Pregnancy X
-statin drug
most commonly used drug in this class of cholesterol-lowering drugs.
- to lower total and LDL cholesterol levels as well as levels of triglycerides.
- raise levels of "good" cholesterol, the HDL component
- can be dosed at any time of day. However, bedtime dosing provides peak drug levels in a time frame that correlates better with the natural diurnal (daytime) rhythm of cholesterol production in the body.
Bile Acid Sequestrants
These drugs are now considered second-line drugs in most cases, less preferred than the more potent statins

- However, they are still a suitable alternative in patients intolerant of the statins.
-Generally these drugs lower the plasma concentrations of LDL cholesterol by 15% to 30%.
- They also increase the HDL cholesterol level by 3% to 8%
- increase hepatic triglyceride and VLDL production, which may result in a 10% to 50% increase in the triglyceride level.
Bile Acid Sequestrantst:
Mechanism of action
- Prevent resorption of bile acids from small intestine
-Bile acids are necessary for the absorption of cholesterol from the small intestine and are also synthesized from cholesterol by the liver. This is one natural way that the liver excretes cholesterol from the body.
-The more that bile acids are excreted in the feces, the more the liver converts cholesterol to bile acids. This reduces the level of cholesterol in the liver and thus in the circulation as well.
-The liver then attempts to compensate for the loss of cholesterol by increasing the number of LDL receptors on its surface. Circulating LDL molecules bind to these receptors to be taken up into the liver, which also has the benefit of reducing circulating LDL in the bloodstream.
Bile Acid Sequestrants:
Indications
-Type II hyperlipoproteinemia
-Relief of pruritus associated with partial biliary obstruction (cholestyramine)
-May be used along with statins
Bile Acid Sequestrants:
Adverse Effects & contraindications
contraindications:
drug allergy, biliary or bowel obstruction, and phenylketonuria (PKU)

Adverse effects:
-Constipation
-Heartburn, nausea, belching, bloating
These adverse effects tend to disappear over
time- Increasing fiber and fluid intake may relieve constipation and bloating.
Cholestyramine (Questran)
Bile Acid Sequestrants drug
-contraindicated in patients with a known hypersensitivity to it and in those who have complete biliary obstruction or PKU.
-It may interfere with distribution of the proper amounts of fat-soluble vitamins to the fetus or nursing infant of a pregnant or nursing woman taking the drug. -Cholestyramine is now being used for its constipating effect, often given as needed for loose bowel movements.
Niacin (Nicotinic Acid) ) Nicobid
-Vitamin B3
-Lipid-lowering properties require much higher doses than when used as a vitamin
-Effective, inexpensive, often used in combination with other lipid-lowering drugs
Niacin: Mechanism of Action
-Thought to increase activity of lipase, which breaks down lipids
-Reduces the metabolism or catabolism of cholesterol and triglycerides
- In large doses, it may produce vasodilatation that is limited to the cutaneous vessels. This effect seems to be induced by prostaglandins.
- Niacin also causes the release of histamine, which results in an increase in gastric motility and acid secretion.
-
Niacin: Indications
-Effective in lowering triglyceride, total serum cholesterol, and LDL levels
-Increases HDL levels
-Effective in the treatment of types IIa, IIb, III, IV, and V hyperlipidemias
Niacin: Adverse Effects & contraindications
Contraindications: liver disease, hypertension, peptic ulcer and active hemorrhagic procress

adverse effects:
-Flushing (caused by histamine release)
-Pruritus
-GI distress
- small doses of aspirin or nonsteroidal antiinflammatory drugs (NSAIDs) may be taken 30 minutes before the niacin dose to minimize the cutaneous flushing. These undesirable effects can also be minimized by starting patients on a low initial dosage and increasing it gradually, and by having patients take the drug with meals.
niacin
drug profile
d
very effective, inexpensive medication that, as previously mentioned, has beneficial effects on LDL cholesterol, triglyceride, and HDL cholesterol levels.

- Drug therapy with niacin is usually initiated at a small daily dose taken with or after meals to minimize the adverse effects previously discussed.

- Liver dysfunction has been observed in individuals taking sustained-release forms of niacin, but not immediate-release forms. However, newer extended-release dosage forms, which dissolve more slowly than the immediate-release forms but faster than the sustained-release forms, appear to have even better adverse effect profiles, including less hepatotoxicity and flushing of the skin.

- Niacin is contraindicated in patients who have shown a hypersensitivity to it; in those with peptic ulcer, hepatic disease, hemorrhage, or severe hypotension; and in lactating women.
- It is also not recommended for patients with gout.
Fibric Acid Derivatives (also known as fibrates): Mechanism of Action
-Believed to work by activating lipase, which breaks down cholesterol
-Also suppress the release of free fatty acid from adipose tissue, inhibit synthesis of triglycerides in the liver, and increase secretion of cholesterol in the bile
Fibric Acid Derivatives: Indications
all decrease the triglyceride level and increase the HDL cholesterol level by as much as 25%.

- Treatment of types III, IV, and V hyperlipidemias
Fibric Acid Derivatives:
Adverse Effects and contraindications
Contraindications:
- rug allergy and may include severe liver or kidney disease, cirrhosis, and gallbladder disease.

Adverse Effects:
-Abdominal discomfort, diarrhea, nausea
-Blurred vision, headache
-Increased risk of gallstones
-Prolonged prothrombin time
-Liver studies may show increased function
Gemfibrozil (Lopid)
Fibrate

-decreases the synthesis of apolipoprotein B and lowers the VLDL level. It can also increase the HDL level. In addition, it is highly effective for lowering plasma triglyceride levels.
-
Cholesterol Absorption Inhibitor:
ezetimibe (Zetia)
- currently the only cholesterol absorption inhibitor
(Lilley et al. Pharmacology and the Nursing Process, 6th
-Inhibits absorption of cholesterol and related sterols from the small intestine
-Results in reduced total cholesterol, LDL, and triglyceride levels
-Also increases HDL levels
-Often combined with a statin drug
-Clinical usefulness has been questioned; new trials underway
-Currently recommended only when patients have not responded to other therapy
Herbal Product: Garlic
-Used as an antispasmodic, antihypertensive, antiplatelet, lipid reducer
-Adverse effects: dermatitis, vomiting, diarrhea, flatulence, antiplatelet activity
-Possible interactions with warfarin, diazepam
-May enhance bleeding when taken with NSAIDs
Herbal Product: Flax
-Both the seed and oil of the plant are used
-Uses: atherosclerosis, hypercholesterolemia, GI distress, menopausal symptoms
-May cause diarrhea and allergic reactions
-Possible interactions: antidiabetic drugs, anticoagulant drugs
Herbal Product: Omega-3
Fatty Acids
-Fish oil products
-Used to reduce cholesterol
-May cause rash, belching, allergic reactions
-Potential interactions with anticoagulant drugs
Nursing Implications
-Assess dietary patterns, exercise level, weight, height, VS, tobacco and alcohol use, family history
- Contraindications include biliary obstruction, liver dysfunction, active liver disease
- Obtain baseline liver function studies
-Patients on long-term therapy may need supplemental fat-soluble vitamins (A, D, K)
-Take with meals to decrease GI upset
- Counsel patient concerning diet and nutrition on an ongoing basis
-Instruct patient on proper procedure for taking the medications
-Powder forms must be taken with a liquid, mixed thoroughly but not stirred, and NEVER taken dry
- Other medications should be taken 1 hour before or 4 to 6 hours after meals to avoid interference with absorption
- To minimize adverse effects of niacin, start on low initial dose and gradually increase it, and take with meals
- Small doses of aspirin or NSAIDs may be taken 30 minutes before niacin to minimize cutaneous flushing
- Inform patients that these drugs may take several weeks to show effectiveness