title: Active transport of nitrofurantoin into human milk.
abstract: OBJECTIVE
  To determine the extent to which nitrofurantoin is transferred into human milk.
  
  
  METHODS
  Prospective, single-dose pharmacokinetic study.
  
  
  METHODS
  University-affiliated clinical research center.
  
  
  METHODS
  Four healthy lactating women 8-26 weeks postpartum.
  
  
  METHODS
  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.
  
  
  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.
authors.affiliation: Division of Pharmacy Practice and Science, College of Pharmacy, University of Kentucky, Lexington 40536-0082, USA.
authors.forename: P M
authors.initials: PM
authors.lastname: Gerk
authors.forename: R J
authors.initials: RJ
authors.lastname: Kuhn
authors.forename: N S
authors.initials: NS
authors.lastname: Desai
authors.forename: P J
authors.initials: PJ
authors.lastname: McNamara
mesh_terms: D000284:Administration, Oral; D000328:Adult; D019540:Area Under Curve; D001693:Biological Transport, Active / Q000502:physiology; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D008895:Milk, Human / Q000378:metabolism*; D009582:Nitrofurantoin / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D011446:Prospective Studies
chemical_list: D009582:Nitrofurantoin