C07AB03

A cardioselective beta-blocker β1 adrenergic used in the treatment of high blood pressure (HBP), angina pectoris, myocardial infarction, cardiac arrhythmias and in the prophylaxis of migraine. Oral administration once a day.

It is excreted in breastmilk in varying quantities but which could be clinically significant, being able to exceed 10% relative dose. ^{(Lwin 2018, Eyal 2010, Hebert 2005, Schmimmel 1989, Atkinson 1988, Kulas 1984, Thorley 1983)}

Varying levels have been measured in the plasma or urine of infants whose mothers were taking it ^{(Lwin 2018, Schmimmel 1989, Fowler 1984, Thorley 1983, Liedholm 1982 and 1981)}, although some authors have not found detectable levels in the plasma or urine of infants. ^{(Eyal 2010, Kulas 1984, White 1984)}

In general, no problems have been observed in infants whose mothers were taking this medication ^{(Eyal 2010, Kulas 1984, White 1984, Fowler 1984, Thorley 1983, Liedholm 1982)}, except for a newborn who, at 5 days of age, presented bradycardia, cyanosis and hypothermia; the mother was taking 50 mg/12 hours of atenolol for postpartum hypertension; the symptoms disappeared when the mother discontinued the medication ^{(Schmimmel 1989)}. A case of drowsiness has been described in an infant whose mother was taking propranolol and other medications ^{(Ho 1999)} and a case of excessive weight loss at 17 days in a low-weight newborn whose mother was also taking mexiletine. ^{(Lownes 1987)}

Hyperprolactinemia and galactorrhea have been observed with the use of atenolol. ^{(Lee 1982)}

Within the same group, there are drugs with a safer pharmacokinetic profile for breastfeeding (higher protein binding, shorter half-life and lower oral bioavailability ^{(Tamargo 2011, Riant 1986)} and that are known not to cause problems during breastfeeding (Anderson 2018). Safer alternatives are preferred during breastfeeding, especially during the neonatal period and in case of prematurity. ^{(Lwin 2018, Malachias 2016, Davanzo 2014, Hutchinson 2013, Rowe 2013, Ghanem 2008, Hale 2003, WHO 2002, Shannon 2000)}