The Amount of Fluvoxamine in Milk Is Unlikely to Be a Cause of Adverse Effects in Breastfed Infants

The aim of this study was to characterize milk/plasma (M/P) ratio, as well as relative infant dose and well-being, in 2 breastfeeding women taking fluvoxamine. The women (37 and 34 years old) and their infants (26 and 0.75 months old) were studied over a 24-hour dose interval at steady state. Fluvoxamine concentrations were measured by high-performance liquid chromatography. Infant exposure was measured as concentration in milk multiplied by an estimated milk production of 0.15 L/kg/d and normalized to the weight-adjusted maternal dose. M/P values of 1.34 and 1.21 were calculated for subjects 1 and 2, respectively, and relative infant doses were estimated to be 1.38% and 0.8%, respectively. No adverse effects in the infants were detected by the mother or on clinical examination, and fluvoxamine was not detected in the infants’ plasma (limit of detection 2 µ g/L). These limited data support the prescription of fluvoxamine to breastfeeding mothers after a careful, individual risk/benefit analysis is undertaken.