Poster Presentation Society of Obstetric Medicine of Australia and New Zealand ASM 2018

Maternal metyrapone use during breastfeeding: safe for the breastfed infant (#54)

Madeline Duke 1 2 , Helen Barrett 1 3 , Carel Pretorius 4 , Fiona Britten 1 , Peter Donovan 5
  1. Obstetric Medicine, Royal Brisbane and Womens Hospital, Brisbane, Qld, Australia
  2. Endocrinology, Royal Brisbane and Women's Hospital, Brisbane, Qld, Australia
  3. Endocrinology, Mater Hospital, Brisbane, Qld, Australia
  4. Pathology, Royal Brisbane and Women's Hospital, Brisbane, Qld, Australia
  5. Clinical Pharmacology, Royal Brisbane and Women's Hospital, Brisbane, Qld, Australia

Context: Metyrapone is an inhibitor of endogenous adrenal corticosteroid synthesis which has been proven to be a viable and safe option in controlling maternal serum cortisol concentrations during pregnancy. The infant exposure to maternally ingested metyrapone through breast milk is, however, largely unknown.


Case Description: We report the excretion of metyrapone into breast milk and subsequent infant exposure from a lactating woman on 250mg of metyrapone three times daily. At steady state, the average concentrations in milk and absolute and relative infant doses (AID and RID) were 176 ug/L, 26.45 ug/kg/d, and 0.7% respectively for metyrapone, and 310 ug/L, 46.52 ug/kg/d, and 1.21% for its active metabolite rac-metyrapol. The breastfed infant was found to have a plasma metyrapone concentration of 4 ug/L, with no evidence of disruption to his adrenocortical axis biochemically.


Conclusion: These findings indicate that maternal metyrapone use during breastfeeding did not pose a significant risk to the breastfed infant.

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