Medications and the Breastfeeding Mother

Estimation of Atenolol Transfer Into Milk and Infant Exposure During Its Use in Lactating Women

“…Factors determining drug transfer from maternal blood circulation to the alveolar lumen in the mammary gland are molecular weight, maternal plasma protein binding, pKa, and lipid solubility of the drug and its pharmacokinetics (Anderson & Sauberan, 2016; Berlin, 2013; Hale & Rowe, 2017). Increased drug transport into milk is favored if the drug has low molecular weight, has low or no binding to maternal plasma proteins, has no charge, has high lipophilicity, attains high concentrations in maternal plasma, and passes into the brain easily (Anderson & Sauberan, 2016; Berlin, 2013; Hale & Rowe, 2017). The relatively high concentration of atenolol was observed in mother’s milk because atenolol has low molecular weight, low protein binding, high PKa, and high milk-to-plasma ratio.…”

“…Atenolol is a hydrophilic compound, according to Hale and Rowe (2017), and has a relatively low molecular weight (266.34 g/mol), low protein binding (5%), and a previously suggested high milk-to-plasma ratio (Berlin, 2013; Hale, 2012; Ito & Lee, 2003). Therefore, it is likely to transfer in the maternal milk via passive diffusion, but the rate and extent of transfer are highly variable and may depend on pH gradients, free-fraction, lipid contents, and the drug dose used by the mother (Anderson & Sauberan, 2016; Hale & Rowe, 2017).…”