Introduction: Women with Chagas disease receiving treatment with nifurtimox are discouraged from breastfeeding. Many patients who would receive treatment with nifurtimox live in extreme poverty, have limited access to resources such as clean water and baby formula and may not have safe alternatives to breast milk.
Aim: We aimed to estimate, using limited available pharmacokinetics data, potential infant exposure to nifurtimox through breast milk.
Methods: Original nifurtimox plasma concentrations were obtained from published studies. Pharmacokinetic parameters were estimated using nonlinear mixed effect modeling with NONMEM version VI. One thousand nifurtimox plasma-concentration profiles were simulated and used to calculate the amount of drug that an infant would be exposed to, if breastfed 150 ml/kg/day.
Results: Breast milk concentrations on the basis of peak plasma levels (1,361 ng/ml) and milk-plasma ratio were estimated. We calculated infant nifurtimox exposure of a breastfed infant of a mother treated with this drug to be below 10% of the maternal weight-adjusted dose, even if milk – plasma ratio were overestimated. Simulation led to similar estimates.
Discussion: Risk for significant infant exposure to nifurtimox through breast milk seems small and below the level of exposure of infants with Chagas disease receiving nifurtimox treatment. This potential degree of exposure may not justify discontinuation of breastfeeding.