title: Atenolol in human plasma and breast milk.
abstract: To assess the problem of continuing atenolol in a breast-feeding mother with hypertension associated with thyrotoxicosis, studies were performed to determine simultaneous plasma and breast milk concentrations of atenolol after a single dose of 50 mg and on continuous therapy of varying weekly dosages. Peak atenolol concentrations in breast milk were 3.6 times higher than simultaneous plasma atenolol concentrations after single-dose administration and 2.9 times higher after continuous-dose administration. A single plasma concentration obtained in the infant following a peak level feeding was less than 10 ng/ml. Although it would seem unlikely that the amount of atenolol excretion in breast milk should warrant interruption of breast-feeding because of maternal medication with ordinary doses, the infant should be evaluated for signs of beta-blockade.
mesh_terms: D000328:Adult; D001262:Atenolol / Q000097:blood / Q000378:metabolism*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000378:metabolism; D007231:Infant, Newborn; D008895:Milk, Human / Q000032:analysis*; D011247:Pregnancy; D011644:Puerperal Disorders / Q000097:blood / Q000378:metabolism
chemical_list: D001262:Atenolol