Studies on administration of thiamazole to breast-feeding mothers with Graves' disease

Setsuko Murase, Toru Sato, Hideya Kokubun, Toshimi Kimura, Masaaki Takahashi, Mitsuru Machida, Shigehiko Shimada, Takashi Nishikawa, Tsunehide Oyama, Mayumi Mochizuki, Yoshifumi Abe, Kunihiko Ito

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)775-782
Number of pages8
JournalJapanese Journal of Clinical Pharmacology and Therapeutics
Issue number6
Publication statusPublished - 1999
Externally publishedYes


  • Antithyroid drug
  • Breast milk
  • Lactation
  • Mothers with Graves' disease
  • Pharmacokinetics of thiamazole

ASJC Scopus subject areas

  • Pharmacology
  • Pharmacology (medical)


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