title: Gentamicin excretion and uptake from breast milk by nursing infants.
abstract: OBJECTIVE
  To investigate the excretion of gentamicin into human breast milk and resulting serum gentamicin levels in nursing newborn infants.
  
  
  METHODS
  Women delivered by cesarean received gentamicin, 240 mg/day (80 mg intramuscularly three times a day) for 5 days postpartum. On day 4, maternal serum samples were collected 1 and 7 hours after gentamicin administration. Milk samples were collected 1, 3, 5, and 7 hours following administration. The infants were fed 1 hour after gentamicin administration, and serum samples were collected from the newborns 1 hour later. The concentrations of gentamicin were measured by a fluorescence polarization immunoassay.
  
  
  RESULTS
  The mean (+/- standard deviation) maternal serum gentamicin levels at 1 and 7 hours were 3.94 +/- 1.12 and 1.02 +/- 0.78 microgram/mL, respectively. Milk gentamicin levels were: 0.42 +/- 0.26, 0.48 +/- 0.17, 0.49 +/- 0.17, and 0.41 +/- 0.25 microgram/mL at 1, 3, 5, and 7 hours, respectively. The mean milk:plasma gentamicin ratios were 0.11 and 0.44 at 1 and 7 hours, respectively. The correlation between maternal peak serum levels and milk levels was not statistically significant (P > .05). Detectable (above 0.27 microgram/mL) gentamicin levels were found in five of the ten newborn serum samples, with a mean level of 0.41 +/- 0.05 microgram/mL.
  
  
  CONCLUSIONS
  Gentamicin is transferred into breast milk, and half of nursing newborn infants have detectable serum gentamicin levels.
authors.affiliation: Department of Obstetrics and Gynecology, Dokuz Eylul University Hospital, Izmir, Turkey.
authors.forename: M
authors.initials: M
authors.lastname: Celiloglu
authors.forename: S
authors.initials: S
authors.lastname: Celiker
authors.forename: H
authors.initials: H
authors.lastname: Guven
authors.forename: Y
authors.initials: Y
authors.lastname: Tuncok
authors.forename: N
authors.initials: N
authors.lastname: Demir
authors.forename: O
authors.initials: O
authors.lastname: Erten
mesh_terms: D000328:Adult; D001942:Breast Feeding; D005260:Female; D005839:Gentamicins / Q000008:administration & dosage / Q000378:metabolism* / Q000493:pharmacokinetics; D006801:Humans; D007231:Infant, Newborn / Q000097:blood*; D008895:Milk, Human / Q000378:metabolism*; D049590:Postpartum Period
chemical_list: D005839:Gentamicins