Transfer of reboxetine into breastmilk, its plasma concentrations and lack of adverse effects in the breastfed infant.

OBJECTIVE

To investigate the transfer of reboxetine into milk, the absolute and relative infant doses via milk and to assess plasma concentrations and adverse unwanted effects in the breastfed infant.

METHODS

Multiple samples of blood and milk were obtained over a dose interval at steady-state from four women who were taking reboxetine for postnatal depression. Drug concentrations in plasma and milk were measured by high performance liquid chromatography and milk/plasma ratio (M/P), absolute infant dose and relative infant dose were estimated by standard methods. Their four, breastfed, infants were also examined clinically, and a blood sample was taken for drug analysis.

RESULTS

The median (range) dose taken by the women was 6 (4-10) mg/day. There was no significant difference in reboxetine concentration between paired fore-and hind-milk samples. The mean (95% CI) M/P was 0.06 (0.03, 0.09). Absolute infant dose was 1.7 (0.7, 2.4) microg/kg/day for reboxetine while the relative infant dose was 2.0% (1.3, 2.7%). Three of the infants met normal developmental milestones and no adverse effects were seen in any infant. The fourth infant had developmental problems that were not associated with the maternal reboxetine therapy. The concentrations of reboxetine in plasma from the four infants were <4 microg/l, 2.6 microg/l, 2.3 microg/l and 5 microg/l, respectively.

CONCLUSION

The study suggests that reboxetine use by lactating women is safe for the breastfed infant. Nevertheless, our study had only four mother/baby pairs, and each decision to breastfeed should always be made on the basis of an individual risk/benefit analysis.