Active transport of nitrofurantoin into human milk.
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.
Gerk
P M
PM
Division of Pharmacy Practice and Science, College of Pharmacy, University of Kentucky, Lexington 40536-0082, USA.
Kuhn
R J
RJ
Desai
N S
NS
McNamara
P J
PJ
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
D009582:Nitrofurantoin