Active transport of nitrofurantoin into human milk

Pharmacotherapy. 2001 Jun;21(6):669-75. doi: 10.1592/phco.21.7.669.34574.


Study objective: To determine the extent to which nitrofurantoin is transferred into human milk.

Design: Prospective, single-dose pharmacokinetic study.

Setting: University-affiliated clinical research center.

Patients: Four healthy lactating women 8-26 weeks postpartum.

Intervention: All subjects received a single, oral, 100-mg dose of nitrofurantoin macrocrystals with food. Serial serum and milk samples were obtained and analyzed by high-performance liquid chromatography.

Measurements and main results: Milk pH, milk fat partitioning, and protein binding in serum and milk were determined. Predicted milk:serum ratio (M:S) was compared with the observed M:S. Nitrofurantoin M:S predicted was 0.28+/-0.05, whereas M:S observed was 6.21+/-2.71. Average milk concentration was 1.3 mg/L, and estimated suckling infant dosage was 0.2 mg/kg/day or 6% of maternal dose (mg/kg).

Conclusions: Nitrofurantoin is actively transported into human milk, achieving concentrations in milk greatly exceeding those in serum. Concern is warranted for suckling infants younger than 1 month old, or for infants with a high frequency of glucose-6-phosphate dehydrogenase deficiency or sensitivity to nitrofurantoin.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Administration, Oral
  • Adult
  • Area Under Curve
  • Biological Transport, Active / physiology
  • Chromatography, High Pressure Liquid
  • Female
  • Humans
  • Milk, Human / metabolism*
  • Nitrofurantoin / administration & dosage
  • Nitrofurantoin / blood
  • Nitrofurantoin / pharmacokinetics*
  • Prospective Studies


  • Nitrofurantoin