Transfer of epinastine to infants through human breast milk.

The purpose of this study was to develop an analytical method for analyzing epinastine in breast milk and maternal plasma samples to determine the safety of epinastine in breastfed infants. Six nursing mothers took epinastine hydrochloride (20 mg) once a day for 7 days, while a nursing mother took it for 30 days. Breast milk and blood samples were collected 2, 4, and 10 h after administration from the volunteers. A liquid chromatography-mass spectrometry system was used to analyze samples pretreated by liquid-liquid extractions. The concentration of epinastine in human milk was 10.3-33.5 ng/mL after 2 h, 9.1-63.8 ng/mL after 4 h, and 8.3-28.9 ng/mL after 10 h. The increase achieved 4 h after administration indicates that epinastine was transferred into human breast milk. However, the milk-to-plasma ratio had a wide range (0.82-3.39), while the relative infant dose at 4 h was 0.36-2.49%, which is lower than the safety level of transferability (10%). Moreover, the plasma levels of epinastine in two infants were slightly below the quantification limit. Overall, our results suggested that epinastine can safely be used by nursing mothers without affecting their infants.

The significance of breast milk biotinidase.

Biotinidase (EC 3.5.1.12) activity in human breast milk was first demonstrated by us, using a newly developed method. The enzyme activity was relatively low compared with that in human serum. However, its activity increased significantly with thiol-reactive agents. Taurine and glutathione also enhanced the enzyme activity considerably. From these results, we speculate that biotinidase in milk would be protected from various inactivation-mechanisms in the same manner as milk lipase. Biotinidase might play an important role in the intestinal absorption of the indispensable vitamin, biotin, during infancy, when enzymes in the pancreatic juice are still immature.