Is Carbimazole Safe in Breastfeeding

I am a breastfeeding mother and i want to know if it is safe to use Carbimazole? Is Carbimazole safe for nursing mother and child? Does Carbimazole extracts into breast milk? Does Carbimazole has any long term or short term side effects on infants? Can Carbimazole influence milk supply or can Carbimazole decrease milk supply in lactating mothers?

Pro-drug which is metabolized to methimazole that is equivalent to 60% of drug. Excretion into breast milk is insignificant (Low 1979, Johansen 1972, Rylance 1987).No adverse effects reported in breastfed infants (Rylance 1987). Plasma levels in those infants were shown to be very low (Rylance 1987). Daily dose up to 30 mg has shown to be safe for the infant (Lamberg 1984, Verd 1998, Bartalena 2005) at both short term (hormone serum level) and long term (psychomotor development).follow-up. The American Academy of Pediatrics rates us as compatible with breastfeeding

Carbimazole is not approved for marketing in the United States by the U.S. Food and Drug Administration, but is available in other countries. It is a prodrug for methimazole which has been studied extensively during breastfeeding; maternal methimazole therapy does not affect thyroid function or intellectual development in breastfed infants with doses up to 20 mg daily. Doses of carbimazole of 30 mg daily or 50 mg weekly have not adversely affected the few breastfed infants studied and no cases of thyroid function alteration has been reported among infants exposed to methimazole via breastmilk. The American Thyroid Association recommends only monitoring infants for appropriate growth and development during routine pediatric health and wellness evaluations and routine assessment of serum thyroid function in the child is not recommended.[1] Rare idiosyncratic reactions (e.g., agranulocytosis) might occur, and the infant should be watched for signs of infection. Monitoring of the infant's complete blood count and differential is advisable if there is a suspicion of a drug-induced blood dyscrasia.

Eleven mothers were taking oral carbimazole in dosages ranging from 5 to 20 mg daily during pregnancy and 5 to 15 mg daily during breastfeeding (extent not stated). None of the 12 infants, including one set of twins, had a serum thyroxine (T4) concentration below the lower limit of normal on day 4 of life. Thyrotropin (TSH) concentrations were normal in all infants when measured at various times over the first 21 days postpartum.[5] A mother with twins began taking carbimazole 30 mg daily 2 months postpartum. The dosage was lowered as she became euthyroid. The infants were breastfed (extent not stated) and clinical and laboratory examinations were performed over the following 4 months. There was no evidence of alterations in thyroid function.[4] A mother was taking carbimazole 50 mg once weekly during pregnancy and postpartum. Her infant was exclusively breastfed for the first 84 days of life and had clinical and laboratory examinations performed over the first 4 months of life. Although the infant's tone and deep tendon reflexes were slightly increased and she was easily irritable, serum thyroid hormone levels were normal as was her growth. No symptoms or signs of hypothyroidism were observed.[6]