A group of resins used to bind certain components of bile in the gastrointestinal tract.
Bile acid sequestrants disrupt the enterohepatic circulation of bile acids by combining with bile constituents and preventing their reabsorption from the gut.
Classified as hypolipidemic agents, although they may be used for purposes other than lowering cholesterol.
These agents lower LDL cholesterol levels synergistically with statins and could play a useful role at low doses.
They are used in the treatment of chronic diarrhea due to bile acid malabsorption.
Are polymeric compounds that serve as ion-exchange resins.
Bile acid sequestrants exchange anions such as chloride ions for bile acids, binding bile acids and sequester them from the enterohepatic circulation.
Poorly tolerated at high doses because of G.I. adverse affects.
The liver then produces more bile acids to replace those that have been lost, and because the body uses cholesterol to make bile acids, this reduces the amount of LDL cholesterol circulating in the blood.
Bile acid sequestrants are large polymeric structures, and they are not significantly absorbed from the gut into the bloodstream, and are excreted via the feces after passage through the gastrointestinal tract along with any bile acids bound to the drug.
As bile acids are biosynthesized from cholesterol, disruption of bile acid reabsorption will decrease cholesterol levels, in particular, low-density lipoproteins.
These drugs have been used for the treatment of hypercholesterolemia and dyslipidemia.
Statins are more efficacious than bile acid sequestrants at lowering LDL.
Occasionally used as an adjunct to the statins as an alternative to the fibrates which are thought to increase the risk of rhabdomyolysis when used with statins.
The bile-acid-binding resins can raise triglycerides by about 5%.
The bile-acid-binding resins should not be used if the triglycerides are elevated.
Chronic diarrhea may be caused by excess bile salts entering the colon rather than being absorbed at the small intestine.
Bile acid malabsorption occurs after surgery to the ileum, in Crohn’s disease, with a number of other gastrointestinal causes, or is commonly a primary, idiopathic condition.
Bile salt diarrhea can also be a side-effect of gallbladder removal.
Bile acid sequestrants are the principal therapy for bile acid-induced diarrhea.
Doses for diarrhea may not need to be as high as those used for hyperlipidemia.
Bile acid sequestrants may improve diarrhea, but bloating and abdominal pain can worsen.
May be used for the prevention of pruritus in patients with chronic liver disease. I May also be used to treat hyperthyroidism by inhibiting the enterohepatic circulation, increasing L-thyroxine loss through defecation, thus lowering body thyroxine levels.
Has been used in the treatment of Clostridium difficile infections, in order to absorb toxins A and B.
As bile acid sequestrants stay in the gut they do not have systemic side-effects.
They may cause constipation, diarrhea, bloating and flatulence.
Some patients may complain of the bad taste.
Not well-absorbed from the gut, so they are safe in pregnant women.
They can interfere with vitamin absorption, causing vitamin deficiencies that may affect the fetus.
Vitamin supplementation may be considered, with appropriate intervals between dosing of the vitamins and bile acid sequestrants.
May also bind drugs in the GI tract, preventing their absorption into the bloodstream.
Should be spaced several hours apart from other drugs.
They can also bind fat-soluble vitamins, such as vitamin A, vitamin D, vitamin E, and vitamin K.
Could result in a vitamin deficiency, and so checking blood levels and possible supplementation has been suggested.
Three drugs are members of this class; all are synthetic polymeric resins:
Cholestyramine
Colestipol
Colesevelam