Last update Jan. 9, 2023


Very High Risk

Very unsafe. Contraindicated. Use of an alternative or cessation of breastfeeding. Read the Comment.

It is a selective aromatase inhibitor (estrogen synthetase), which inhibits the secretion of estrogen. 
Indicated in the treatment of breast cancer in postmenopause. Oral administration once a day for several years.

Since the last update we have not found published data on its excretion in breastmilk.

Its high plasmatic protein binding and very wide volume of distribution make it difficult to pass into breast milk.

Pharmacokinetics show that after 3 elimination half-lives (T½) 87.5% of the drug is eliminated from the body; after 4 T½ it is 94%, after 5 T½, 96.9%, after 6 T½, 98.4% and after 7 T½ it is 99%. From 7 T½ the plasma concentrations of the drug in the body are negligible. In general, a period of at least five half-lives can be considered a safe waiting period before breastfeeding again (Anderson 2016).

According to this data, the interruption of breastfeeding would be for a period of between 5 days (5 T½) to 7 days (7 T½) after the administration of the last dose.

Its administration every 24 hours over many years make it impossible to continue breastfeeding.

See below the information of this related product:

  • Maternal Cancer ( Poorly safe. Evaluate carefully. Use safer alternative or interrupt breastfeeding 3 to 7 T ½ (elimination half-lives). Read the Comment.)


We do not have alternatives for Exemestane.

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

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Exemestane in other languages or writings:


Main tradenames from several countries containing Exemestane in its composition:


Variable Value Unit
Oral Bioavail. 42 %
Molecular weight 296 daltons
Protein Binding 90 %
VD 285 l/Kg
Tmax 1 hours
24 hours


  1. AEMPS. Exemestano. Ficha técnica. 2022 Full text (in our servers)
  2. Apotex. Exemestane. Drug Summary. 2020 Full text (in our servers)

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