Transfer of mepindolol to newborns by breast-feeding mothers after single and repeated daily doses.

The concentrations of mepindolol in plasma and milk of five breastfeeding mothers were determined after 1 and 5 daily doses of mepindolol sulphate 20 mg. In the newborns plasma levels were measured once on the first and fifth days of the study. The mean maternal plasma concentration of mepindolol 2 h after administration was 52 ng/ml both after 1 and 5 doses; in the milk 18 and 22 ng/ml the corresponding concentrations were. The average plasma/milk drug concentration ratio was 2.6 +/- 1.6. Plasma levels in the newborn were below the detection limit of 1 ng/ml, except for one baby in whom 2 and 5 ng/ml, respectively, were found 4 h after one and five maternal doses.