Although current guidelines for antibiotic prophylaxis recommend the administration of narrow-spectrum antibiotics ( cefazolin ) after clamping of the umbilical cord , the data suggest that antibiotic administration before surgical incision or the use of extended-spectrum regimens ( involving azithromycin or metronidazole ) after cord clamp may reduce postcesarean maternal infection by up to 50 % .
: The use of either cefazolin alone before surgical incision or an extended-spectrum regimen after cord clamp seems to be associated with a reduction in  postcesarean maternal infection .
Maternal and transplacental pharmacokinetics of azithromycin.
OBJECTIVE The purpose of this study was to characterize the pharmacokinetics of orally administered azithromycin in the term gravid woman . STUDY DESIGN Twenty women who were scheduled for elective cesarean delivery were enrolled prospect ively and received 1 g of oral azithromycin at either 6 , 12 , 24 , 72 , or 168 hours before the operation . All women received spinal anesthesia , at which time a sample of cerebrospinal fluid was obtained for analysis . Maternal serum and urine were obtained immediately before the operation . Intraoperatively , sample s of myometrium , maternal adipose tissue , placenta , amniotic fluid , and umbilical arterial and venous cord blood were obtained . Azithromycin levels were determined quantitatively with high-pressure liquid chromatography with electrochemical detection . RESULTS All participants tolerated the preoperative azithromycin without significant adverse reactions . Peak maternal serum azithromycin levels occurred within 6 hours of drug administration . Although high serum levels of azithromycin  were reached early , a rapid decline in drug concentration was noted over the initial 24 hours after the drug administration ( 6-hour : 311 ng/mL ; 24-hour : 63 ng/mL ) . In contrast ,  azithromycin levels in myometrial , adipose , and placental tissue were higher ( > 500 ng/mL ) and sustained for up to 72 hours after administration . High urine levels of azithromycin  ( > 5000 ng/mL ) were noted similarly during the initial 72 hours after drug administration . Umbilical arterial and venous serum azithromycin levels were low ( 19 - 38 ng/mL ) during the first 72 hours . Amniotic fluid levels were highest at 6 hours ( 151 ng/mL ) and declined rapidly . Maternal cerebrospinal azithromycin concentrations were undetectable for all time points . CONCLUSION Azithromycin has a rapid serum half-life in the term gravid woman with a prolonged half-life and high-sustained antibiotic levels noted within myometrium , adipose , and placental tissue . Given the broad antimicrobial spectrum and placental penetration , azithromycin may have potential use for the treatment of perinatal infections
Although current guidelines for antibiotic prophylaxis recommend the administration of narrow-spectrum antibiotics ( cefazolin ) after clamping of the umbilical cord , the data suggest that antibiotic administration before surgical incision or the use of extended-spectrum regimens ( involving azithromycin or metronidazole ) after cord clamp may reduce postcesarean maternal infection by up to 50 % .
: The use of either cefazolin alone before surgical incision or an extended-spectrum regimen after cord clamp seems to be associated with a reduction in  postcesarean maternal infection .