Cholestyramine (Questran) binds liothyronine and other thyroid in hormones in the intestine, reducing the absorption and levels of liothyronine. Thyroid hormones should not be administered for 4 to 5 hours after administering cholestyramine.
The administration of liothyronine increases the action of the blood thinning drug, warfarin (Coumadin). Warfarin acts by reducing the concentration of factors in the body that are necessary for blood to clot. The concentration of these clotting factors in the body is determined by the body's rate of metabolism. In theory, by increasing the body's metabolism (elimination) of these clotting factors, thyroid hormones reduce the body's ability to clot and therefore enhance the effects of warfarin. Since this can lead to excessive bleeding, the dose of warfarin may need to be reduced.
PREGNANCY: Thyroid hormones do not easily cross the placenta and, therefore, are safe for pregnant women to take.
NURSING MOTHERS: Very small amounts of thyroid hormone may be excreted in breast milk. This is not a serious problem for breastfed infants.
Medically reviewed by Eni Williams, PharmD
Reference: FDA Prescribing Information
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