Cholestyramine Dosing in Hyperthyroidism
The recommended dose of cholestyramine for hyperthyroidism is 8-16 g/day orally divided into 2 doses, with lower doses of 2-4 g twice daily often being effective and better tolerated as adjunctive therapy to conventional treatments. 1, 2
Dosing Guidelines
- Standard cholestyramine dosing for hyperthyroidism ranges from 8-16 g/day divided into two doses 1
- Lower doses of 2-4 g/day (1-2 g twice daily) have been shown to be effective and well-tolerated as adjunctive therapy in clinical studies 2
- Gradual dose titration is recommended to minimize side effects, typically starting at 2-4 g/day and increasing based on clinical response 1
- The maximum recommended dose is 24 g/day, though this higher dose may require divided administration due to the volume involved 3
Mechanism of Action in Hyperthyroidism
- Cholestyramine binds thyroid hormones in the intestine, interrupting their enterohepatic circulation 2, 4
- This binding increases fecal excretion of thyroid hormones, leading to more rapid reduction in serum thyroid hormone levels 5, 4
- Studies show cholestyramine produces a more rapid and complete decline in thyroid hormone levels when added to conventional therapy 4
Clinical Evidence for Efficacy
- In a randomized, double-blind, placebo-controlled trial, low-dose cholestyramine (1-2 g twice daily) added to methimazole and propranolol resulted in faster normalization of thyroid hormone levels compared to conventional therapy alone 2
- Patients receiving cholestyramine showed a 61% reduction in total T4, 78% reduction in free T4, and 68% reduction in T3 levels, compared to 43%, 65%, and 50% reductions respectively in the control group 4
- Cholestyramine has been successfully used in cases of refractory hyperthyroidism that failed to respond to conventional therapies 5, 6
Administration Considerations
- Cholestyramine can be administered once or twice daily without reference to meals 3
- Other medications should be taken at least 1 hour before or 4 hours after cholestyramine to avoid impeding their absorption 1
- This is particularly important for thyroid hormone replacement therapy, as cholestyramine can increase TSH in patients receiving such treatment 1
Adverse Effects and Precautions
- Common side effects include constipation, dyspepsia, and nausea 1
- May exacerbate hypertriglyceridemia 1
- Post-marketing reports include increased TSH in patients receiving thyroid hormone replacement therapy, bowel obstruction, dysphagia, esophageal obstruction, and fecal impaction 1
- Contraindicated in patients with complete biliary obstruction or history of serious hypersensitivity to the medication 1
Special Considerations
- Cholestyramine is particularly useful as adjunctive therapy in preparing patients with refractory hyperthyroidism for thyroidectomy 6
- It may be especially valuable in patients who experience hepatotoxicity from thionamides or have contraindications to other conventional therapies 6
- The clinical response to cholestyramine in hyperthyroidism can be rapid, with significant decreases in free T4 observed within 5-12 days of initiation 5