Background: Solid organ transplant recipients are usually advised against breastfeeding because of the questionable safety of immunosuppressants. Limited data suggest that infant exposure to tacrolimus via milk is low. This report characterizes the milk-to-blood ratio for tacrolimus using area under the concentration-time curve analysis in a renal transplant patient.
Case: A 29-year-old woman was exclusively breastfeeding her healthy 3-month-old infant while on tacrolimus 4 mg daily plus other drugs relevant to her transplant. The milk-to-blood ratio was 0.23, and average tacrolimus concentrations in milk were 1.8 microg/L. The baby ingested approximately 0.5% of the maternal dose (weight-adjusted).
Conclusion: Infant exposure to tacrolimus in milk is very low, suggesting that maternal tacrolimus therapy may be compatible with breastfeeding.