Sulphasalazine and sulphapyridine serum levels in children to mothers treated with sulphasalazine during pregnancy and lactation.

Serum concentrations of sulphasalazine and sulphapyridine were measured during the first week of life in 15 children whose mothers had been on sulphasalazine during pregnancy. The serum concentrations of sulphapyridine and sulphasalazine were similar in the children and their mothers at delivery. The elimination rate of the drugs in the newborn children was slow but the concentrations were not so high that a bilirubin displacing effect could be expected. In eight mothers who were breast-feeding and taking sulphasalazine, analyses were done of mothers' serum, breast-milk and serum from their children. The results showed that the amount of sulphasalazine and sulphapyridine transferred to the child via the breast-milk is negligible with regard to the risk of kernicterus. It is concluded that a woman in need of sulphasalazine treatment can continue the medication throughout pregnancy and lactation without risk of development of kernicterus in her child. Only term infants without haemolytic disease were included in the study. Thus our conclusion is not necessarily valid for the prematurely born child or the child with haemolytic disease.