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Metyrapone use while Breastfeeding

Drugs containing Metyrapone: Metopirone

Medically reviewed on September 7, 2017

Metyrapone Levels and Effects while Breastfeeding

Summary of Use during Lactation

Evidence from one patient indicates that amounts of metyrapone and its active metabolite in breastmilk are very small and unlikely to adversely affect a breastfed infant. Exposure of the infant can be further minimized by avoiding nursing for 2 to 2.5 hours after each dose.

Drug Levels

Maternal Levels. A woman was taking metyrapone 250 mg orally 4 times daily during pregnancy and postpartum. At 1 week postpartum, milk samples were obtained before the midday dose and at 1.25, 2.25, 3.25, 4.24 and 5.25 hours after the dose. Samples were analyzed for metyrapone and its active metabolite racemic metyrapol. Peak milk concentrations of the drug and metabolite occur at 1.25 hours after the dose; by 2.25 hours after the dose, milk levels had dropped by about 75%. Half-lives in milk were 3.63 hours for metyrapone and 34 hours for metyrapol, respectively. The authors calculated that the combined dose a fully breastfed infant would receive is 9 mcg/kg daily or 0.1% of the weight-adjusted maternal dosage.[1]

Infant Levels. Relevant published information was not found as of the revision date.

Effects in Breastfed Infants

Relevant published information was not found as of the revision date.

Effects on Lactation and Breastmilk

Relevant published information was not found as of the revision date. Women taking metyrapone chronically for suppression of hypercorticism associated with Cushing's syndrome may have other hormonal abnormalities that might interfere with lactation.


1. Hotham NJ, Ilett KF, Hackett LP et al. Transfer of metyrapone and its metabolite, rac-metyrapol, into breast milk. J Hum Lact. 2009;25:451-4. PMID: 19759353

Metyrapone Identification

Substance Name


CAS Registry Number


Drug Class


Enzyme Inhibitors

Administrative Information

LactMed Record Number



Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.

Further information

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