Aims The objective of this study was to measure the secretion of the s
elective serotonin uptake citalopram in breast milk. Methods The excre
tion of citalopram in breast milk was studied at steady-state conditio
ns in two patients with depression and in one healthy volunteer after
ingestion of a single dose citalopram. Results Milk/serum concentratio
n ratios based on single pairs of samples from the two patients ranged
from 1.16 to 1.88. Based on milk concentration data from the patients
, the absolute dose ingested by a suckling infant would be 4.3-17.6 mu
g kg(-1) day(-1), and the relative dose 0.7-5.9% of the weight-adjust
ed maternal dose. Based on area-under-the-time-concentration curves fr
om the healthy volunteer, the milk/serum ratio was 1.00, the absolute
dose to the infant during steady-state conditions would be 11.2 mu g k
g(-1) day(-1) and the relative 1.8% of the weight-adjusted maternal do
se. Conclusion The study shows that the relative dose to a suckling in
fant is close to that reported for fluoxetine, and higher than reporte
d for fluvoxamine, paroxetine and sertraline.