Q: 46 years old female is admitted to ICU with symptoms consistent with exacerbation of her hyperthyroidism symptoms. The endocrinology service started the patient on methimazole. Patient's home list of medications shows Cholestyramine in it. Cholestyramine will make affect of methimazole? (select one)
A) better
B) worse
Answer: A
For patients who require rapid amelioration of hyperthyroid symptoms, Cholestyramine is a good adjunctive therapy to add with methimazole. It lowers serum T4 and T3 concentrations more rapidly than methimazole alone and resolves hyperthyroid symptoms rapidly.
It is given in a dose of 4 g four times daily with methimazole.
Mechanism of Action: Thyroid hormones are metabolized in the liver and are conjugated with glucuronide and sulfate. The conjugation products are excreted in the bile. Free thyroid hormones are released and reabsorbed in the intestine. Bile acid sequestrants like cholestyramine interfere with this enterohepatic circulation and recycling of thyroid hormone.
Caution: Since cholestyramine can interfere with the absorption of oral medications, other drugs given orally should be given two hours before or two hours after cholestyramine administration. Cholestyramine may be discontinued when clinical status improves.
#endocrinology
#pharmacology
References:
1. Solomon BL, Wartofsky L, Burman KD. Adjunctive cholestyramine therapy for thyrotoxicosis. Clin Endocrinol (Oxf) 1993; 38:39.
2. Kaykhaei MA, Shams M, Sadegholvad A, et al. Low doses of cholestyramine in the treatment of hyperthyroidism. Endocrine 2008; 34:52.
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