Citalopram and desmethylcitalopram concentrations in breast milk and in serum of mother and infant.

A case is presented with measurements of the selective serotonin reuptake inhibitor (SSRI)-antidepressant citalopram in serum of mother and breast-fed infant and in breast milk. We found a milk-to-serum concentration ratio of approximately 3 for both citalopram and the main metabolite desmethylcitalopram. Peak milk concentrations of citalopram occurred 3-9 h after drug intake by the mother. The infant received approximately 5% of the mother's dose, adjusted for weight. Accordingly, the serum level in the infant of approximately 7 nM corresponded to approximately 1/15 of the trough serum concentration of the mother (104 nM). No signs of drug effects in the infant were observed.