Atenolol pharmacokinetics and excretion in breast milk during the first 6 to 8 months postpartum

Sara Eyal, Joong D. Kim, Gail D. Anderson, Megan L. Buchanan, Debra A. Brateng, Darcy Carr, David E. Woodrum, Thomas R. Easterling, Mary F. Hebert

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


The objectives were to evaluate the time course for atenolol pharmacokinetics in lactating women postpartum and to quantify atenolol plasma concentrations in the women's 3-to 4-month-old nursing infants. Data were collected during 1 dosing interval from lactating women treated with atenolol for therapeutic reasons, at 2 to 4 weeks (n = 32), 3 to 4 months (n = 22), and 6 to 8 months (n = 17) postpartum. A single blood sample was collected from 15 nursing infants (3-4 months of age) of the mothers participating in the study. At 2 to 4 weeks, 3 to 4 months, and 6 to 8 months postpartum, atenolol infant doses, relative to the mother's weight-adjusted dose, were 14.6% ± 7.6%, 8.3% ± 5.2% and 5.9% ± 2.9%, respectively. Over this time, maternal atenolol pharmacokinetics did not change to a clinically significant extent. Atenolol concentrations were below assay quantification limits (<10 ng/mL) in the plasma of all 3-to 4-month-old nursing infants studied. These findings support the careful use of atenolol during breastfeeding, because in the vast majority of healthy, term infants, atenolol concentrations will be too low to be clinically relevant. Premature infants and those with kidney disease require further study. Infant exposure depends on maternal dose and decreases during the first 6 to 8 months postpartum.

Original languageAmerican English
Pages (from-to)1301-1309
Number of pages9
JournalJournal of Clinical Pharmacology
Issue number11
StatePublished - Nov 2010
Externally publishedYes


  • Atenolol
  • breast milk
  • kidney function
  • pharmacokinetics
  • postpartum


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