Bile acid sequestrants are medications that bind bile acids in the gastrointestinal tract, preventing the gut from reabsorbing the acids. In doing so, they help lower blood levels of LDL cholesterol, the so-called “bad” cholesterol. Bile acid sequestrants also can slightly increase levels of the “good” cholesterol, which is known as HDL. Generic names for these medications include cholestyramine and colesevelam. They are sold under brand names such Questran®, Welchol™ and Colestid®:.
These medications work to reduce cholesterol because the body uses cholesterol to produce bile acids. When bile acid sequestrants are taken, they prevent the body from reusing bile acids. As a result, the body must make more bile acids, using up cholesterol to do so. This, in turn, lowers blood LDL cholesterol levels.
When taken as prescribed, bile acid sequestrants can reduce LDL cholesterol levels by 10 to 25 percent while increasing HDL cholesterol levels by 3 to 5 percent. These medications often are prescribed in conjunction with cholesterol-lowering statins to enhance the effects of both drugs. In combination, these two medications can reduce LDL cholesterol levels by as much as 50 percent.
Although bile acid sequestrant medications are considered to be safe for long-term use, they can cause some unpleasant side effects. Possible effects include bloating, a sensation of stomach fullness, nausea, gas and constipation. These side effects relate to the way in which the medication works in the gastrointestinal tract. Some of the side effects can be alleviated by adding more fiber to the diet and getting regular exercise. Sequestrant medications also can reduce the absorption of certain vitamins, so vitamin supplements might be necessary for people who take sequestrants.
Another potential side effect of these medications is that they can increase triglyceride levels. Triglycerides are a type of fatty acid that is found in the blood. In small amounts, they are necessary for good health, but in large amounts, they are considered to be a risk factor for coronary artery disease. For this reason, some people with high triglyceride levels might not be able to use bile acid sequestrant medications.
Bile acid sequestrants can decrease the absorption of other types of medications, including digoxin, diurectics, synthetic thyroid hormones and blood thinners such as warfarin. Therefore, these medications can become less effective if taken at the same time as sequestrants. For this reason, people who take sequestrants in addition to other medications are advised to take the other medications either one hour before or four hours after taking the sequestrant.
