Bile acid sequestrant
The bile acid sequestrants are a group of resins used to bind certain components of
Mechanism
Bile acid sequestrants are
Bile acid sequestrants are large polymeric structures, and they are not significantly absorbed from the gut into the bloodstream. Thus, bile acid sequestrants, along with any bile acids bound to the drug, are excreted via the feces after passage through the gastrointestinal tract.[3]
Medical uses
Hyperlipidemia
As bile acids are biosynthesized from cholesterol, disruption of bile acid reabsorption will decrease cholesterol levels, in particular, low-density lipoprotein (commonly known as "bad cholesterol") in blood. Consequently, these drugs have been used for the treatment of hypercholesterolemia and dyslipidemia.[4][5][6]
Use of these agents as
Bile acid malabsorption
Chronic diarrhea may be caused by excess bile salts entering the colon rather than being absorbed at the end of the small intestine (the ileum). This condition of 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. The SeHCAT test can be used for diagnosis. Bile salt diarrhea can also be a side-effect of gallbladder removal.[1]
Bile acid sequestrants are the principal therapy for bile acid-induced diarrhea.
Use in other conditions
In chronic
Bile acid sequestrants may also be used to treat
Cholestyramine has been used in the treatment of
Side effects
As bile acid sequestrants are designed to stay in the gut; in general, they do not have systemic side effects. However, they may cause problems in the gastrointestinal tract, such as constipation, diarrhea, bloating, and flatulence. Some patients complain of the bad taste.
Because bile acid sequestrants are not well-absorbed from the gut, they are generally regarded as safe in pregnant women. However, by interfering with vitamin absorption (see below), they could cause vitamin deficiencies that may affect the fetus. So, vitamin supplementation may be considered, with appropriate intervals between dosing of the vitamins and bile acid sequestrants.
Drug interactions
In addition to bile acids, bile acid sequestrants may also bind drugs in the GI tract, preventing their absorption into the bloodstream. For this reason, it is generally advised that bile acid sequestrants be spaced several hours apart from other drugs.[8]
Vitamins
They can also bind
Examples
Three drugs are members of this class; all are synthetic polymeric resins:[1]
- Cholestyramine(generic and various proprietary names)
- Colestipol (Colestid, Colestipid)
- Colesevelam (Cholestagel in Europe, Welchol in the US, Lodalis in Canada)