Bile acid sequestrants are a class of medications designed to help manage cholesterol levels in the blood. These drugs work by targeting substances produced by the liver that aid in digestion. They contribute to lowering low-density lipoprotein (LDL) cholesterol, often referred to as “bad” cholesterol.
What Bile Acid Sequestrants Are and How They Work
Bile acid sequestrants are non-absorbable polymers that function within the gastrointestinal tract. They are essentially resins that bind to bile acids.
Bile acids are compounds produced in the liver from cholesterol and are stored in the gallbladder. When food is consumed, bile acids are released into the small intestine to help digest fats and absorb fat-soluble vitamins. After aiding digestion, most bile acids are normally reabsorbed from the small intestine and returned to the liver to be reused in a continuous cycle known as enterohepatic circulation.
Bile acid sequestrants interrupt this cycle by forming a complex with bile acids in the intestine. This binding prevents the reabsorption of bile acids back into the bloodstream. Instead, the bound bile acid-drug complex is excreted from the body through feces.
The liver then senses a depletion in its bile acid pool. To compensate for this loss, the liver increases its production of new bile acids. Since cholesterol is a primary building block for bile acids, the liver draws more cholesterol from the bloodstream to meet this increased demand. This process effectively lowers the amount of LDL cholesterol circulating in the blood.
Conditions Treated
Bile acid sequestrants are primarily prescribed to reduce high cholesterol levels, specifically LDL cholesterol. They can lower LDL cholesterol by approximately 15% to 30%. These medications are often used in combination with statins or as a standalone treatment for individuals who cannot tolerate statins due to side effects.
Beyond cholesterol management, these sequestrants also address other medical conditions. They are effective in treating chronic diarrhea caused by bile acid malabsorption, a condition where excess bile acids enter the colon and trigger digestive upset. By binding these excess bile acids, the drugs help to solidify stools and alleviate diarrhea.
Additionally, bile acid sequestrants can relieve pruritus, or severe itching, associated with certain liver conditions where bile acids accumulate in the skin. Some formulations, such as colesevelam, are also approved to help manage blood sugar levels in adults with type 2 diabetes.
Commonly Prescribed Sequestrants
Several bile acid sequestrants are available, each with distinct characteristics. Cholestyramine is commonly known by brand names such as Questran and Prevalite. It is available as a powder that must be mixed with liquid before consumption.
Colestipol is marketed under brand names like Colestid. It comes in both powder and tablet forms.
Colesevelam is known by the brand name Welchol. It is available as tablets, a chewable bar, and a powder for suspension. Colesevelam has a lower potential for drug interactions compared to older sequestrants.
Important Information for Patients
When taking bile acid sequestrants, specific administration guidelines help maximize effectiveness and minimize side effects. It is advised to take these medications with meals or immediately before them to reduce gastrointestinal issues like bloating and constipation. Powder forms should be thoroughly mixed with water, juice, or other non-carbonated liquids.
Gastrointestinal side effects are common. Patients may experience constipation, abdominal discomfort, gas, and nausea. Increasing dietary fiber and fluid intake can help manage constipation.
Bile acid sequestrants can bind to other medications and fat-soluble vitamins (A, D, E, K), potentially reducing their absorption and effectiveness. To avoid this, it is recommended to take other medications at least one hour before or four to six hours after a bile acid sequestrant dose. Patients should always discuss all current medications, including over-the-counter drugs and supplements, with their healthcare provider to prevent potential interactions.
Regular monitoring is important to assess the medication’s effectiveness and to check for any nutrient deficiencies, particularly of fat-soluble vitamins, which can occur with long-term use. Adherence to the prescribed regimen and maintaining a healthy diet are also important components of treatment.