Hypolipidemic Agents 1&2 Flashcards
What is hyperlipoproteinemia?
Occurs when the blood triacylglyceraol (TAG or triglycerides) or cholesterol in lipoproteins exceeds normal
Elevated lipoprotein accelerates development of the three types of atherosclerosis, they are?
Peripheral vascular disease
Ischemic cardiovascular disease
Coronary heart disease (CHD or myocardial infarction)
What accounts for a half of adult deaths in the U.S. each year?
Atherosclerosis
When does risk begin for hyperlipoproteinemia?
Risk begins at levels of cholesterol previously considered normal
What is the pathology of atherosclerosis?
Monocytes migrate to the endothelial cells of the artery wall where macrophages engulf LDL (low density lipoprotein) and are transformed into foam cells that are cholesterol esters and form plaques on the artery wall
What is the implication of drug therapy on decreasing CHD?
Hypolipidemic drug therapy has decreased CHD mortality continuously as more drugs are approved.
Mostly due to statins
What is the suggestion surrounding statins?
Statins can prevent cardiac events in patients with cholesterol levels thought to be normal
What are the two pathways of lipoprotein synthesis?
Exogenous and endogenous
What is the exogenous pathway?
Dietary lipids (triglycerols, cholesterol, and cholesterol esters) are packaged into chylomicrons in the intestinal mucosal cells. The chylomicrons then travel through the lymphatic system to reach the general circulation where they deliver their lipids to peripheral tissues
What is the endogenous pathway?
The liver synthesizes fatty acids and cholesterol from dietary glucose and uses these in addition to lipids taken up from the blood to produce Very Low Density Lipoproteins (VLDL). These VLDL deliver lipids to peripheral tissues and become Intermediate Density Lipoproteins (IDL) and Low Density Lipoproteins (LDL).
Where does cholesterol synthesis occur
In all cells
What does the synthesis of 1 cholesterol molecule require?”
180 ATPs making it energetically expensive
What is the pathway for degradation of cholesterol?
There is no pathway for degradation of cholesterol
How is cholesterol removed?
Cholesterol is removed by hepatic conversion to bile acids leading to excretion in feces; however some secreted bile acids are recovered by enterohepatic cycling
Where are the carbon atoms of cholesterol derived?
All the carbon atoms of cholesterol are derived from the acetate of Acetyl-CoA
What do statins inhibit?
HMG-CoA Reductase
What does isopentenyl- pyrophosphate turn into in the cholesterol synthesis pathway?
Vitamin E, Ubiquinone (Q10), prenylated proteins
What is cholesterol vitally important for?
Cell membrane stability
Where is VLDL synthesized?
Only in the liver
Where is HDL synthesized?
Only in the liver
Where are chylomicrons secreted?
In the intestines
Which lipoprotein in the largest?
Chylomicrons ( they have the highest percentage TAG)
What are chylomicrons secreted by?
The intestine
Where are chylomicrons secreted?
Into the lymphatic system
Chylomicrons deliver what
Lipids to the muscles and adipose tissue
What do chylomicron remnants bind to?
Remnant receptors
What is the second largest lipoprotein?
VLDL
What is VLDL secreted by?
Secreted by the liver directly into the blood
What does VLDL deliver?
Lipids to the muscle and adipose tissue
What is the end product of VLDL?
VLDL ends up as LDL which binds to LDL receptors on the liver
Chylomicron Remnant Receptor
Part of the LDL receptor family
LDL receptor
Not a transporter
Microsomes Triglyceride Transfer Protein (MTTP)
Transfers hepatic TG from cytosol into the endoplasmic reticulum for packaging into VLDL particles
Scavenger Receptor 1B
A channel to allow HDL lipids into the liver
PCSK9
Proprotein Convertase Subtilisin/Kevin type 9 binds to LDL receptors
Cholesterol Ester Transfer Protein
Exchanges lipids (HDL-LDL)
Hepatic Lipase
Metabolizes triglycerides for hepatic import
Why does the liver need cholesterol?
To make bile acids to process fats
The liver synthesizes
A lipoprotein known as High Density Lipoprotein (HDL)
What is Reverse Cholesterol Transport?
After HDL particles are secreted into the blood by the liver they travel to the peripheral tissues and pick up cholesterol. Cholesterol then esters to bring HDL back to the liver to be metabolized
What is “bad cholesterol”?
LDL particles that become trapped in the blood vessels to produce atherosclerosis
Normal cholesterol values
Total cholesterol < 200mg/dl
Triglycerides < 150 mg/dl
HDL >60 mg/dl
LDL <100 mg/dl
Total/HDL ratio <4
Borderline Risk of ASCVD values
Total cholesterol 200-239 mg/dl
Triglycerides 150-199 mg/dl
HDL 40-50 mg/dl (men); 50-59 mg/dl (women)
LDL 100-190 mg/dl
Total/HDL ratio 4-6
High Risk of ASCVD values
Total cholesterol >240mg/dl
Triglycerides >200 mg/dl
HDL <40 mg/dl (men); <50mg/dl (women)
LDL >190 mg/dl
Total/HDL ratio >6
Major risk factors exclusive of LDL Cholesterol
-Cigarette smoking
-Hypertension (BP >140/90 mmHg) or patient on antihypertensive medication
-Low HDL cholesterol (<40mg/dl; >60 is neg.)
-Family history of CHD (male <55, female <65
-Age (men >45 years; women >55 years)
What are genetic causes of increased LDL?
Familial Hypercholesterolemia
Familial Combined Hyperlipidemia
Polygenic Hypercholesterolemia
Familial Hypercholesterolemia (FH)
-Homo and Heterozygous
-Defect in or lack of functional LDL receptor (LDL receptor gene mutation)
-Excessive accumulation of LDL ( decreased clearance)
Familial Combined Hyperlipidemia
-Excessive production of VLDL by the liver
-Increased levels of both cholesterol & TAG
Polygenic Hypercholesterolemia
-largest number if patients
-abnormal LDL (doesn’t bind to receptors)
-increased sensitivity to saturated fat and cholesterol
-other, unknown causes
Secondary causes if Hyperlipidemia
Diabetes, hypothyroidism, obstructive liver disease, chronic renal failure, drugs that increase LDL-C and decrease HDL-C (progestins, anabolic steroids and corticosteroids)
What encompasses metabolic syndrome?
Abdominal obesity, elevated TAG, low HDL-C, high blood pressure, high fasting glucose
What is the treatment for metabolic syndrome?
Lose weight; treat lipid abnormalities
What do dietary principles do for treating LDL?
-1st line treatment for hyperlipidemia
- Effective in lowering mild elevations of LDL-C
- Saturated fat and cholesterol suppress expression of LDL receptors
-replace saturated fat with:
-monounsaturated fat (olive oil)
-polyunsaturated fat (most vegetable oils)
-carbohydrate (complex)
-no replacement (weight reduction diet)
-obesity and caloric excess lower HDL
-exercise raises HDL
-diets should be tried for 6 months