Elsevier

Obstetrics & Gynecology

Volume 98, Issue 6, December 2001, Pages 1075-1079
Obstetrics & Gynecology

Maternal and transplacental pharmacokinetics of cefazolin

https://doi.org/10.1016/S0029-7844(01)01629-5Get rights and content

Abstract

OBJECTIVE:

To evaluate the intrapartum pharmacokinetics of cefazolin, including delivery to amniotic fluid (AF) and fetal compartments, and to ascertain that adequate cefazolin concentrations are attained to exceed the mean concentration inhibiting 90% (MIC90) of group B streptococcus strains.

METHODS:

Cefazolin (1 g) was administered intravenously at five separate time intervals (0.5, 1, 2, 4, and 6 hours) before elective cesarean at term to 26 women with intact membranes and with no significant infections or cardiovascular, liver, or renal disease. Samples of maternal blood, cord blood, and AF were obtained at the time of delivery. Exact collection times relative to cefazolin infusion were noted. Amniotic fluid contaminated with blood or meconium was excluded. Cefazolin concentration was measured by high-pressure liquid chromatography.

RESULTS:

All maternal and cord plasma cefazolin levels, except one, were above the MIC90 for Streptococcus agalactiae (group B streptococcus). For AF, all cefazolin levels, except two, were above the MIC90.

CONCLUSIONS:

Cefazolin concentrations greater than or equal to the MIC90 for group B streptococcus were attained in nearly all maternal, fetal, and AF samples. This information, together with the knowledge that there is rare resistance of group B streptococcus to cefazolin, supports the use of cefazolin as a better alternative than clindamycin or erythromycin for group B streptococcus prophylaxis in patients with a nonanaphylactic penicillin allergy.

Section snippets

Materials and methods

Term patients undergoing scheduled elective cesarean delivery between September 1999 and January 2001 were candidates for the study. Specific inclusion criteria comprised pregnant patients at term who were 18 years of age or older and not in labor. Women who had ruptured membranes, serious maternal illness, signs of infection, or a history of allergy to penicillin or cephalosporin were excluded. Twenty-six patients enrolled in the study. The Institutional Review Board of the University of

Results

Twenty-six women provided informed consent to participate in this investigation. The women ranged in age from 22 to 40 years (31 ± 5 years [mean ± standard deviation]). The gestational age at delivery was 39 ± 1 week (mean ± standard deviation). Of the 26 women, 20 were white, five were black, and one was Asian. The majority of the patients received regional spinal anesthesia (n = 18), whereas the remainder received epidural anesthesia (n = 8). Six underwent a primary cesarean delivery, five

Discussion

The placental transfer of cefazolin appears quite similar to that of ampicillin, with concentrations greater than the MIC90 achieved rapidly in maternal, cord, and AF compartments. This contrasts with the poor or unpredictable delivery of erythromycin and clindamycin to cord blood and AF. The attainment of the MIC90 for cefazolin against group B streptococcus in the body compartments at 4 hours after infusion is compared with that of other recommended antimicrobial agents for group B

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