Salazosulfapyridine and metabolites in fetal and maternal body fluids with special reference to 5-aminosalicylic acid.

In 7 pregnant women, treated prophylactically with salazosulfapyridine (SASP) 3 g/day, amniotic fluid (16th week, n = 4, maternal and cord plasma (n = 5) and breast milk (n = 3) were analysed for SASP and the metabolites sulfapyridine (SP), acetyl sulfapyridine (Ac-SP), 5-aminosalicylic acid (5-ASA) and acetyl 5-aminosalicylic acid (Ac-5-ASA). Amniotic fluid contained concentrations of SASP, SP and Ac-SP and partly also Ac-5-ASA comparable to those previously found by others, whereas 5-ASA concentrations were very low. The ratios of maternal to cord plasma for all SASP metabolites were about 1:1-1:2, except for 5-ASA, cord plasma being extremely low. In breast milk, only traces of 5-ASA were detected, while Ac-5-ASA was above the plasma level. Only negligible amounts of 5-ASA are thus transferred to the fetus/newborn, which is of significance for the future use of the new non-sulfa-containing 5-ASA preparations during and after pregnancy.