Atenolol pharmacokinetics and excretion in breast milk during the first 6 to 8 months postpartum.
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.
University of Washington Department of Pharmacy, Seattle, WA 98195-7630, USA.
Sara
S
Eyal
Joong D
JD
Kim
Gail D
GD
Anderson
Megan L
ML
Buchanan
Debra A
DA
Brateng
Darcy
D
Carr
David E
DE
Woodrum
Thomas R
TR
Easterling
Mary F
MF
Hebert
D000328:Adult; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D001262:Atenolol / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007774:Lactation; D008297:Male; D008895:Milk, Human / Q000737:chemistry*; D049590:Postpartum Period; D011247:Pregnancy; D013997:Time Factors
D000959:Antihypertensive Agents; D001262:Atenolol