Section 4B Flashcards
What occurs to chylomicrons once they enter the lymphatic circulation?
They are transported upward through the thoracic duct and emptied into the venous circulation at the jugular and subclavian veins
When does lipemia usually occur?
Within an hour after eating a fatty meal. Plasma usually becomes clear within a few hours since chylomicrons have a short half life (<60 min.)
What enzyme is present in capillary endothelium that hydrolyzes the TGs of chylomicrons into fatty acids & glycerol so they can be transported to adipose tissue and liver?
Lipoprotein lipase
What are the 5 classes of lipoproteins?
Chylomicrons Very low density lipoproteins (VLDL) Intermediate density lipoproteins (IDL) Low density lipoproteins (LDL) High density lipoproteins (HDL)
Chylomicrons are synthesized by what?
The enterocytes of the small intestine
Where are the other 4 classes of lipoproteins other than chylomicrons synthesized?
By liver hepatocytes
The naming of lipoproteins is based on the results of what?
Ultracentrifugation by which the lipoproteins are separated according to their density
VLDL contains what?
High TGs/ moderate cholesterol & phospholipids
IDL contains what?
Moderate TGs, cholesterol & phospholipids
LDL contains what?
Low TGs/ high cholesterol & phospholipids
HDL contains what?
Low TGs, cholesterol & phospholipids
What are the only two lipoproteins routinely monitored?
LDL-C & HDL-C
What is the role of LDLs?
Transport cholesterol and other lipids from the liver to the peripheral tissues, making them available for membrane or steroid hormone synthesis
Function of HDLs
to transport excess cholesterol from peripheral tissues to the liver, where it is broken down and becomes part of the bile
what is the most effective drugs currently in use for treating elevated LDL-C?
Statins
Name the 7 statin drugs in the USA market
- Atorvastatin (Lipitor)
- Fluvastatin (Lescol)
- Lovastatin (Altoprev, Mevacor)
- Pravastatin (Pravachol)
- Simvastatin (Zocor)
- Rosuvastatin (Crestor)
- Pitavastatin (Livalo)
What is the general term for any muscle disease?
Myopathy
What is myalgia?
Refers to muscle pain or weakness without increased creatine kinase
What is Myositis?
The same as myalgia but includes elevated Creatine Kinase
What is Rhabdomyloysis?
Muscle symptoms, very high creatine kinase
Increased serum creatinine, often with dark urine and myoglobinuria
What degree of statins (How many?) have been associated with myopathy?
All statins
Approximately how many patients taking statin reports muscle complaints
1 in 10 patients
What are the 7 risk factors for statin myopathy?
- Elderly
- Small size
- High statin dose
- Liver or renal disease
- Diabetes
- Uncontrolled hypothyroidism
- Interacting medications
What was the first lipid-lowering agent that was associated with a reduction in total mortality?
Niacin (Nicotinic Acid, Vitamin B3)
What are the 3 basic preparations of Niacin?
- Immediate (regular) release (IR); crystalline niacin
- Sustained/extended release (SR & ER)
- No-flush (Inositol hexaniacinate; niacinadmide)
What are the two niacin drugs that are IR?
Niacor (Prescription)
Generic (OTC)
What are the two SR & ER niacin drugs?
Niaspan (Prescription (ER))
Slo-Niacin (OTC (SR))
What is the efficacy of No-flush niacin?
They are worthless! Do not affect lipid levels. They do not contain nicotinic acid, which is the active ingredient
How does Niacin work? (Its MOA)
Reduces the production of VLDL which leads to a secondary reduction in LDL. Niacin is the MOST POTENT agent for raising HDL levels.
What is the main adverse effect of niacin?
Intolerance to niacin is common! Only 50-60% of patients may be able to take full doses
- Tingling
- Flushing
- Sensation of warmth in face or upper body
How to blunt the niacin adverse effects?
Taking ASA or other NSAID (ibuprofen) 30-45 minutes prior to each niacin dose blunts this prostaglandin-mediated effect.
What are sometimes considered the safest hypolipidemic drugs and why?
Resins because they are not absorbed from the intestine
name 3 available resins
Colestipol (Colestid)
Cholestyramine (Questran, Questran light)
Colesevelam (Welchol)
What is the MOA of Resins?
They bind bile acids in the intestinal lumen
The MOA of Resins leads to what two things?
Decreased emulsification of dietary fat
Prevention of bile acid reabsorption, this causes liver to increase its production of bile acids, using hepatic cholesterol to do so.
How do Resins affect LDL and HDL levels?
Plasma LDL levels can be reduced by 30%
Resins have little effect on HDL and TGs in blood
What are 6 common adverse effects related to Resins and the GI system?
- Constipation
- Bloating/ abdominal distention/ pain
- flatulence
- Nausea
- Vomiting
- Dyspepsia
What extra supplementation may relieve adverse effects of resins?
Fiber supplement which may relieve constipation and bloating
Resins bind what other durgs that interfere with their absorption?
- Fat soluble vitamins
- Folate
- Thiazides
- Tetracyclines
- Warfarin
- Propanolol
- Penicillin
How do you avoid resin interaction with other drugs?
Take resin a few hours after taking medications that it may interfere with
All H2O absorption in the small intestine is what?
Passive and secondary to solute movement
Where does calcium absorption occur?
Duodenum and Jejunum and is regulated by vitamin D3
How are fat-soluble vitamins (A,D,E&K) absorbed?
Similar to fat
Most water-soluble vitamins are absorbed how?
by simple diffusion
Vitamin B12 requires what for normal absorption?
IF
What cells absorbe IF-Vitamin B12 complexes across the brush border?
Ileal cells
What causes vitamin B12 deficiency?
Atrophy of the gastric mucosa results in a deficiency of IF and acid secretion
How long does it take chyme to move through the entire small intestine via peristalsis?
3-5 hours
Sympathetic nerves generally do what to small intestine?
Inhibit activity while PNS generally excites muscular activity
