Does cholestyramine interfere with the absorption of other oral medications?

From the Guidelines

Cholestyramine does interfere with the absorption of many oral medications, and to minimize these interactions, other medications should be taken at least 1 hour before or 4-6 hours after cholestyramine. This bile acid sequestrant binds to medications in the gastrointestinal tract, preventing their absorption into the bloodstream. Specific medications affected include warfarin, digoxin, thyroid hormones (levothyroxine), certain antibiotics (tetracyclines), fat-soluble vitamins (A, D, E, K), and oral contraceptives 1. The mechanism involves cholestyramine's strong negative charge, which allows it to bind positively charged medications and bile acids, forming insoluble complexes that are excreted in feces rather than absorbed.

Some key points to consider when managing patients on cholestyramine and other oral medications include:

• Separating administration of cholestyramine and other medications by at least 1 hour before or 4-6 hours after cholestyramine to minimize potential interactions 1
• Being aware of the specific medications that may interact with cholestyramine, such as warfarin, digoxin, and thyroid hormones, and monitoring patients closely for signs of reduced efficacy or increased toxicity 1
• Considering alternative medications or formulations that may be less likely to interact with cholestyramine, such as colesevelam, which has a different structure that maximizes interactions with bile salt and reduces the potential for interactions with other drugs 1

It is essential for patients to inform healthcare providers about all medications they're taking to prevent potentially serious drug interactions with cholestyramine. By taking a proactive approach to managing potential interactions, healthcare providers can help minimize the risks associated with cholestyramine and ensure optimal outcomes for their patients.

From the FDA Drug Label

Cholestyramine resin may delay or reduce the absorption of concomitant oral medication such as phenylbutazone, warfarin, thiazide diuretics (acidic) or propranolol (basic), as well as tetracycline, penicillin G, phenobarbital, thyroid and thyroxine preparations, estrogens and progestins and digitalis SINCE CHOLESTYRAMINE RESIN MAY BIND OTHER DRUGS GIVEN CONCURRENTLY, IT IS RECOMMENDED THAT PATIENTS TAKE OTHER DRUGS AT LEAST 1 HOUR BEFORE OR 4 TO 6 HOURS AFTER CHOLESTYRAMINE RESIN (OR AT AS GREAT AN INTERVAL AS POSSIBLE) TO AVOID IMPEDING THEIR ABSORPTION

Yes, cholestyramine may interfere with the absorption of other oral medications.

• The medications that may be affected include:
  • Phenylbutazone
  • Warfarin
  • Thiazide diuretics
  • Propranolol
  • Tetracycline
  • Penicillin G
  • Phenobarbital
  • Thyroid and thyroxine preparations
  • Estrogens and progestins
  • Digitalis
• To minimize the risk of interference, it is recommended to take other medications at least 1 hour before or 4 to 6 hours after cholestyramine resin 2 2.

From the Research

Cholestyramine Interference with Other Oral Medications

• Cholestyramine is a bile acid sequestrant that binds to bile acids in the intestine to form an insoluble complex, which is excreted in the feces 3.
• This mechanism of action may interfere with the absorption of other oral medications, as it can bind to other substances in the intestine.
• A study on the use of cholestyramine in the treatment of digoxin intoxication found that cholestyramine can enhance the elimination of digoxin by interrupting its enterohepatic recycling 4.
• This suggests that cholestyramine may interfere with the absorption or reabsorption of other oral medications that undergo enterohepatic recycling.
• However, the specific effects of cholestyramine on the absorption of other oral medications are not well-studied, and more research is needed to fully understand its potential interactions 3, 4.

Potential Interactions

• Cholestyramine may interact with other oral medications by binding to them in the intestine and reducing their absorption.
• Medications that undergo enterohepatic recycling, such as digoxin, may be particularly affected by cholestyramine 4.
• The clinical significance of these potential interactions is not well-established, and further study is needed to determine the extent to which cholestyramine interferes with the absorption of other oral medications 3, 4.