Lipid Drugs Flashcards
What is Cholestyramine (Questran™, colestipol)?
Cholestyramine is a bile acid sequestrate and removes bile acids from the body by forming insoluble complexes with bile acids in the intestine, which are then excreted in the feces.
As a result of this loss of bile acids, more plasma cholesterol is converted to bile acids in the liver to normalize levels. This conversion of cholesterol into bile acids lowers plasma cholesterol levels.
- Not used much due to adverse drug effects
To what drug class does Cholestyramine belong?
Pharmacologic => bile acid sequestrate
Therapeutic class => cholesterol-lowering agent
Describe the pharmacodynamics of Cholestyramine.
- Cholestyramine forms a non-absorbable complex with bile acids in small bowel (releasing Cl)
- Inhibits enterohepatic reuptake of intestinal bile salts
- Increases fecal loss of bile acids –> increases bile acid synthesis –> increases cholesterol synthesis –> increases expression of LDL receptors on cell surface of hepatocytes
- Reduces LDL chol by 10-20% (maximum)
Describe the pharmacokinetics of Cholestyramine.
- Virtually no absorption
- Excreted in feces
- Peak effect 3 weeks
What toxicity is associated with Cholestyramine?
> 10% of patients have GI problems
- Gas, bloating, diarrhea, constipation
- May interfere with absorption of fat-soluble vitamins, and drugs including digoxin, warfarin, thyroxine
What interactions should be considered for patients on Cholestyramine?
- May diminish absorption of statins, steroids, digoxin, warfarin
What special considerations are made with Cholestyramine?
- Provided as a powder for oral suspension
- Be sure to drink liquids with it
What is the dose for Cholestyramine?
4 gm once a day, up to 6 times per day
What is Nicotinic Acid (niacin/Vit B3, Niacor™, others)?
Niacin has been used for over 50 years to increase levels of HDL in the blood and has been found to decrease the risk of cardiovascular events modestly
To what drug class does Nicotinic Acid belong?
Pharmacologic class => vitamin
Therapeutic class=> cholesterol-lowering agent
Describe the pharmacodynamics of Nicotinic Acid.
- Lowers BOTH TG and LDL-cholesterol
- Decreased production of VLDL –> decreased production of LDL –> increase in LDL receptor in liver
- Modestly effective as single agent, usually used in combination
- Can also raise HDL
Describe the pharmacokinetics of Nicotinic Acid.
- Well absorbed, large first pass effect (to nicotinamide)
- Tmax 45 min
- Half-life 45 min
- Urinary excretion of unchanged drug and metabolite
What toxicity is associated with Nicotinic Acid?
- Many patients develop skin flushing, which can be lessened by taking aspirin
- Some patients develop hepatitis
What interactions should be considered for patients on Nicotinic Acid?
Absorption is decreased by cholestyramine
What special considerations should be made for patients on Nicotinic Acid?
Avoid in patients with CAD and avoid heavy ethanol use
What dose should Nicotinic Acid be given in?
Pellagra 100 mg tid
Hyperlipidemia 0.5-2 gm tid after meals