Can the patient breast-feed her newborn, if she is being treated with sulfasalazine? Can sulfasalazine be used during pregnancy?
A patient with rheumatoid arthritis, who is breast-feeding her child, is being treated with sulfasalazine 2.0 gram per day. Her physician has warned her that she should not breast-feed her child while she is on such therapy. Her gynaecologist would like to know whether it is true, but also whether use of sulfasalazine is permitted during pregnancy.
Sulfasalazine (salazosulphapyridine) is a chemical compound composed of 5-aminosalicylic acid (5-ASA, mesalazine) and sulfapyridine, connected by an azo-linkage (1). The drug is being used for treatment of rheumatic and inflammatory bowel diseases (2) and most of the adverse effects due to the sulfapyridine moiety (3).
Lactation: Sulfasalazine and sulfapyridine pass into the human milk and their concentrations are up to 30% and 30-60% of those found in plasma, respectfully (4,5). A suckling infant ingests about 5.9% of the weight-adjusted maternal daily dose, based on the most common dosage regimen of 2.0 gram per day, which gives rise to an average milk concentration of 10.3 mg per L (3). However, a daily dose of 3.0 gram causes milk concentrations to rise to 35 mg per L and as a result, such infants have a significantly higher intake of sulfasalazine, sulfapyridine and its metabolites, which amounts 10.5% of the weight-adjusted maternal daily dose (3).
In exclusively breast-fed infants, whose mothers were exposed to the higher dose of sulfasalazine, (3.0-4.0 gram per day) bloody diarrhoea occurred (6). With such a significant quantity of ingested sulphonamide derivatives, there is even a theoretical possibility that these molecules could displace bilirubin from it bond with plasma albumins and cause kernicterus. This possibility becomes more realistic in pre-term born infants and in those with haemolysis, due to deficiency of glucose-6-phosphate dehydrogenase activity (7).
Pregnancy: Although sulfasalazine and its metabolites readily cross the placenta and attain in fetus the same concentrations as in the mother´s serum, there are no indications that sulfasalazine has teratogenic effects (8). The Swedish Medical Birth Registry contains data on 698 children born to mothers exposed to sulfasalazine during pregnancy, 29 of which, or 4.2%, had congenital anomalies (expected frequency 3.5%) (9). The only risk is connected with the aforementioned tendency towards bilirubin displacement, which could warrant cease of sulfasalazine medication three to four weeks before delivery (10).
Since sulphonamides impair the activation of folic acid, it is necessary to supplement a pregnant woman treated with sulfasalazine with at least 0.4 mg of folic acid per day, starting with one month before pregnancy and ending with the 12th week of pregnancy (11).
Sulfasalazine can be used during lactation at doses up to 2.0 gram daily. At higher doses, breast-feeding should be avoided.
In utero exposure to sulphasalazine does not seem associated with a substantially increased risk of unwanted fetal effects and can be used during pregnancy. Due to a theoretic risk of kernicterus, treatment should be discontinued four weeks prior to the anticipated delivery. It is recommended to supplement the folic acid with at least 0.4 mg daily, until week 12 of pregnancy.
Senast ändrad 2018-09-20