Oxprenolol placental transfer, plasma concentrations in newborns and passage into breast milk.

Thirty-two pregnant hypertensive patients were treated with oxprenolol administered in combination with dihydralazine as Trasipressol tablets. Before delivery, oxprenolol was demonstrable in the maternal plasma and the amniotic fluid. The free fraction of oxprenolol in the maternal serum (15% +/- 7.8; mean +/- s.d.; n = 25) was similar to that in normal serum. At the end of delivery, oxprenolol was found in both the maternal and umbilical plasma in most cases. Measurable, but low oxprenolol concentrations were present in the newborn plasma. After delivery, oxprenolol was demonstrable in the maternal plasma and breast milk. An infant weighing 3 kg and consuming 500 ml of breast milk per day would receive a maximum dose 60 times less than the normal daily dose for a hypertensive adult (4 mg/kg).