Last update Oct. 4, 2020

H03BB02

Compatible

Safe product and/or breastfeeding is the best option.

An antithyroid used in the treatment of hyperthyroidism.
Oral administration in one to three daily doses.

It is excreted in breastmilk in clinically insignificant amounts (Teller 1980, Low 1979) and no problems have been observed in infants whose mothers were taking it (Rylance 1987). The plasma levels of these infants were undetectable or very low (Azizi 2003-2002).

Maternal doses of up to 20-30 mg per day have been shown to be safe for the infant in the short and long term, with normal T3, T4 and TSH determinations and psychomotor development (Kobaly 2019, Alexander 2017, Serrano 2014, Stagnaro 2011, Inoue 2009, Glatstein 2009, Marx 2008, Bartalena 2005, Mandel 2001, Aziz 2006, 2003, 2002, 2000 and 1996, Cooper 1987, Rylance 1987, Lamberg 1984).

It is not necessary to monitor thyroid function in infants, it is sufficient to monitor adequate physical and psychomotor development (Kobaly 2019, Alexander 2017, Inoue 2009, Marx 2008, Mandel 2001).

To minimize infant exposure, the dose of methimazole should be taken immediately after feeding (Hudzik 2016).

Given the risk of liver toxicity from propylthiouracil, methimazole is considered the preferred treatment for hyperthyroidism, especially during breastfeeding (Karras 2009, 2010 and 2012, Azizi 2011, Serrano 2014, Hudzik 2016).

If doses greater than 30 mg of methimazole are required, switching to propylthiouracil to control hyperthyroidism can be tried (doses up to 450 mg/day while breastfeeding have shown to be safe), or continuing with methimazole but with clinical and analytical monitoring (T4 and TSH) of the infant every 2 weeks at first.

American Academy of Pediatrics: Maternal Medication Usually Compatible With Breastfeeding (AAP 2001)


See below the information of these related products:

Alternatives

We do not have alternatives for H03BB02 since it is relatively safe.

Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

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Other names

H03BB02 is Methimazole in ATC Code/s.

Is written in other languages:

H03BB02 is also known as

Group

H03BB02 belongs to this group or family:

Tradenames

Main tradenames from several countries containing H03BB02 in its composition:

Pharmacokinetics

Variable Value Unit
Oral Bioavail. 95 %
Molecular weight 114 daltons
Protein Binding < 10 %
VD 0.6 l/Kg
Tmax 1 - 2 hours
T½ 3 - 6 hours
M/P ratio 1.3 -
Theoretical Dose 0.006 mg/Kg/d
Relative Dose 1-8 %
Ped.Relat.Dose 1.5 %

References

  1. Kobaly K, Mandel SJ. Hyperthyroidism and Pregnancy. Endocrinol Metab Clin North Am. 2019 Sep;48(3):533-545. Abstract
  2. Alexander EK, Pearce EN, Brent GA, Brown RS, Chen H, Dosiou C, Grobman WA, Laurberg P, Lazarus JH, Mandel SJ, Peeters RP, Sullivan S. 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum. Thyroid. 2017 Abstract Full text (link to original source) Full text (in our servers)
  3. Serrano Aguayo P, García de Quirós Muñoz JM, Bretón Lesmes I, Cózar León MV. Tratamiento de enfermedades endocrinológicas durante la lactancia. [Endocrinologic diseases management during breastfeeding.] Med Clin (Barc). 2015 Jan 20;144(2):73-9. Abstract
  4. Lazarus JH. Pre-conception counselling in graves' disease. Eur Thyroid J. 2012 Abstract Full text (link to original source) Full text (in our servers)
  5. Karras S, Krassas GE. Breastfeeding and antithyroid drugs: a view from within. Eur Thyroid J. 2012 Abstract Full text (link to original source) Full text (in our servers)
  6. Fumarola A, Di Fiore A, Dainelli M, Grani G, Carbotta G, Calvanese A. Therapy of hyperthyroidism in pregnancy and breastfeeding. Obstet Gynecol Surv. 2011 Abstract
  7. Azizi F, Amouzegar A. Management of hyperthyroidism during pregnancy and lactation. Eur J Endocrinol. 2011 Abstract Full text (link to original source) Full text (in our servers)
  8. Stagnaro-Green A, Abalovich M, Alexander E, Azizi F, Mestman J, Negro R, Nixon A, Pearce EN, Soldin OP, Sullivan S, Wiersinga W; American Thyroid Association Taskforce on Thyroid Disease During Pregnancy and Postpartum.. Guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and postpartum. Thyroid. 2011 Abstract Full text (link to original source) Full text (in our servers)
  9. Karras S, Tzotzas T, Kaltsas T, Krassas GE. Pharmacological treatment of hyperthyroidism during lactation: review of the literature and novel data. Pediatr Endocrinol Rev. 2010 Abstract
  10. Inoue M, Arata N, Koren G, Ito S. Hyperthyroidism during pregnancy. Can Fam Physician. 2009 Abstract Full text (link to original source) Full text (in our servers)
  11. Karras S, Tzotzas T, Krassas GE. Antithyroid drugs used in the treatment of hyperthyroidism during breast feeding. An update and new perspectives. Hormones (Athens). 2009 Abstract Full text (link to original source) Full text (in our servers)
  12. Glatstein MM, Garcia-Bournissen F, Giglio N, Finkelstein Y, Koren G. Pharmacologic treatment of hyperthyroidism during lactation. Can Fam Physician. 2009 Abstract Full text (link to original source) Full text (in our servers)
  13. Azizi F. Treatment of post-partum thyrotoxicosis. J Endocrinol Invest. 2006 Abstract
  14. Törnhage CJ, Grankvist K. Acquired neonatal thyroid disease due to TSH receptor antibodies in breast milk. J Pediatr Endocrinol Metab. 2006 Abstract
  15. Koren G, Soldin O. Therapeutic drug monitoring of antithyroid drugs in pregnancy: the knowledge gaps. Ther Drug Monit. 2006 Abstract Full text (link to original source) Full text (in our servers)
  16. Bartalena L, Tanda ML, Bogazzi F, Piantanida E, Lai A, Martino E. An update on the pharmacological management of hyperthyroidism due to Graves' disease. Expert Opin Pharmacother. 2005 Abstract Full text (link to original source) Full text (in our servers)
  17. Nice FJ, De Eugenio D, Dimino TA, Freeny IC, Rovnack MB, Gromelski JS. Medications and Breast-Feeding: A Guide for Pharmacists, Pharmacy Technicians, and Other Healthcare Professionals. Part I. J Pharm Technol 2004;20:17-27. doi: 10.1177/875512250402000106.
  18. Azizi F, Bahrainian M, Khamseh ME, Khoshniat M. Intellectual development and thyroid function in children who were breast-fed by thyrotoxic mothers taking methimazole. J Pediatr Endocrinol Metab. 2003 Abstract
  19. Azizi F. Thyroid function in breast-fed infants is not affected by methimazole-induced maternal hypothyroidism: results of a retrospective study. J Endocrinol Invest. 2003 Abstract
  20. Azizi F, Hedayati M. Thyroid function in breast-fed infants whose mothers take high doses of methimazole. J Endocrinol Invest. 2002 Abstract
  21. Mandel SJ, Cooper DS. The use of antithyroid drugs in pregnancy and lactation. J Clin Endocrinol Metab. 2001 Abstract Full text (link to original source) Full text (in our servers)
  22. AAP - American Academy of Pediatrics Committee on Drugs. Transfer of drugs and other chemicals into human milk. Pediatrics. 2001 Sep;108(3):776-89. Abstract Full text (link to original source) Full text (in our servers)
  23. Azizi F, Khoshniat M, Bahrainian M, Hedayati M. Thyroid function and intellectual development of infants nursed by mothers taking methimazole. J Clin Endocrinol Metab. 2000 Abstract Full text (link to original source) Full text (in our servers)
  24. Verd S, Cardo E. Well-being of a baby breast fed by her mother on carbimazol treatment. J Hum Lact. 1998 Abstract
  25. Azizi F. Effect of methimazole treatment of maternal thyrotoxicosis on thyroid function in breast-feeding infants. J Pediatr. 1996 Abstract
  26. Rylance GW, Woods CG, Donnelly MC, Oliver JS, Alexander WD. Carbimazole and breastfeeding. Lancet. 1987 Abstract
  27. Cooper DS. Antithyroid drugs: to breast-feed or not to breast-feed. Am J Obstet Gynecol. 1987 Abstract
  28. Lamberg BA, Ikonen E, Osterlund K, Teramo K, Pekonen F, Peltola J, Välimäki M. Antithyroid treatment of maternal hyperthyroidism during lactation. Clin Endocrinol (Oxf). 1984 Abstract
  29. Cooper DS, Bode HH, Nath B, Saxe V, Maloof F, Ridgway EC. Methimazole pharmacology in man: studies using a newly developed radioimmunoassay for methimazole. J Clin Endocrinol Metab. 1984 Abstract
  30. Johansen K, Andersen AN, Kampmann JP, Mølholm Hansen JM, Mortensen HB. Excretion of methimazole in human milk. Eur J Clin Pharmacol. 1982 Abstract
  31. Kampmann JP, Hansen JM. Clinical pharmacokinetics of antithyroid drugs. Clin Pharmacokinet. 1981 Abstract
  32. Tegler L, Lindström B. Antithyroid drugs in milk. Lancet. 1980 Abstract
  33. Low LC, Lang J, Alexander WD. Excretion of carbimazole and propylthiouracil in breast milk. Lancet. 1979 Abstract

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