Excretion of bupropion in breast milk.

Objective: To measure the excretion of bupropion and its metabolites in breast milk. A secondary objective was to determine whether the drug accumulated in the nursing infant.

Case Summary: Milk and plasma samples were collected from a woman taking bupropion 300 mg/d in divided doses who was breastfeeding her 14-month-old son. A single plasma sample was collected from the infant.

Results: After a 100-mg dose, the peak bupropion breast milk concentration measured at two hours was 0.189 micrograms/mL. Milk-to-plasma ratios ranged from 2.51 to 8.58 over a six-hour interval. Two of three metabolites also were measured in milk. Bupropion and its metabolites were not detected in the single plasma sample obtained from the infant.

Conclusions: Bupropion accumulates in human breast milk in concentrations much higher than in maternal plasma. Two metabolites are also excreted into the milk. Neither bupropion nor its metabolites were detected in the infant's plasma, indicating that accumulation did not occur in this infant.