We investigated the excretion of thiamazole, an antithyroid drug, in the milk of 6 mothers with Graves' disease. Thiamazole in serum or milk was determined by high performance liquid chromatography. The mothers had been taking thiamazole 5∼10 mg/day, before and after delivery. The drug concentration in serum was almost equal to that in milk; it reached maximum at about 2 hours after the previous administration and was considerably decreased at 12 hours. The babies were breast-fed at 12 hours or more after the previous administration, and the drug was not detected (below about 1 ng/ml) in the serum of any baby. Thyroid function test results were normal in all babies. These findings suggest that breast-feeding mothers with hyperthyroidism can continue thiamazole treatment, though further study is needed for assessment of safety, regarding the accumulation of the drug in the thyroid of babies.
|Japanese Journal of Clinical Pharmacology and Therapeutics
|Published - 1999
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