Aims: To investigate the transfer of escitalopram and its demethyl metabolite into milk, the absolute and relative infant doses via milk and to assess any unwanted effects in the breastfed infant.
Methods: Multiple samples of blood and milk were obtained over a dose interval at steady state from eight women who were taking escitalopram for postnatal depression. Drug concentrations in plasma and milk were measured by high-performance liquid chromatography and milk/plasma ratio (M/P(AUC)), absolute infant dose and relative infant dose were estimated by standard methods. Their breastfed infants were also examined clinically and in five infants a blood sample was taken for drug analysis.
Results: The median dose taken by the women was 10 mg day(-1). The mean (95% confidence interval) M/P(AUC) was 2.2 (2.0, 2.4) for escitalopram and 2.2 (1.9, 2.5) for demethylescitalopram. Absolute infant doses were 7.6 microg kg(-1) day(-1) (5.2, 10.0) for escitalopram and 3.0 microg kg(-1) day(-1) (2.4, 3.6) for demethylescitalopram. The total relative infant dose for escitalopram plus its demethyl metabolite was 5.3% (4.2, 6.4) as escitalopram equivalents. All of the infants had met normal developmental milestones and no adverse effects were seen. Compared with average maternal plasma concentrations (24 microg l(-1)), the concentrations of the parent drug and its metabolite in plasma from five infants were most commonly below the limit of detection (</=3 microg l(-1)).
Conclusion: The study shows that escitalopram is safe for use during breastfeeding. Because its absolute infant dose is lower than that for an equivalent antidepressant dose of rac-citalopram, it may be preferred over rac-citalopram in treating depression in lactating women. Nevertheless, each decision to breastfeed should always be made on the basis of an individual risk:benefit analysis.