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Colestyramine (INN) or cholestyramine (USAN) (trade names Questran, Questran Light, Cholybar, Olestyr) is a bile acid sequestrant, which binds bile in the gastrointestinal tract to prevent its reabsorption. It is a strong ion exchange resin, which means it can exchange its chloride anions with anionic bile acids in the gastrointestinal tract and bind them strongly in the resin matrix. The functional group of the anion exchange resin is a quaternary ammonium group attached to an inert styrene-divinylbenzene copolymer. Cholestyramine 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. ==Medical uses== Bile acid sequestrants such as cholestyramine were first used to treat hypercholesterolemia, but since the introduction of statins, now have only a minor role for this indication. They can also be used to treat the pruritus, or itching, that often occurs during liver failure and other types of cholestasis where the ability to eliminate bile acids is reduced. Cholestyramine is commonly used to treat diarrhea resulting from bile acid malabsorption. It was first used for this in Crohn's disease patients who had undergone ileal resection. The terminal portion of the small bowel (ileum) is where bile acids are reabsorbed. When this section is removed, the bile acids pass into the large bowel and cause diarrhea due to stimulation of chloride/fluid secretion by the colonocytes resulting in a secretory diarrhea. Cholestyramine prevents this increase in water by making the bile acids insoluble and osmotically inactive. Cholestyramine is also used in the control of other types of bile acid diarrhea. The primary, idiopathic form of bile acid diarrhea is a common cause of chronic functional diarrhea, often misdiagnosed as diarrhea-predominant irritable bowel syndrome (IBS-D), and most of these patients respond to cholestyramine. It is beneficial in the treatment of postcholecystectomy syndrome chronic diarrhea. Cholestyramine is also useful in treating Post-vagotomy diarrhea. Cholestyramine can be helpful in the treatment of ''Clostridium difficile'' infections, to adsorb toxins A and B, and reduce the diarrhea and the other symptoms these toxins cause. However, because it is not an anti-infective, it is used in concert with vancomycin. It is also used in the "wash out" procedure in patients taking leflunomide or teriflunomide to aid drug elimination in the case of drug discontinuation due to severe side effects caused by leflunomide or teriflunomide. A case report suggests that Cholestyramine may be useful for cyanobacterial (microcystin) poisoning in dogs.〔 〕 Ointments containing cholestyramine compounded with aquaphor have been used in topical treatment of diaper rash in infants and toddlers.〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「cholestyramine」の詳細全文を読む スポンサード リンク
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