Carbenicillin

 Risk Factor: B
 Class: ANTI-INFECTIVES / Penicillins

Contents of this page:

Fetal Risk Summary
Breast Feeding Summary
References
Questions and Answers

Fetal Risk Summary

Carbenicillin is a penicillin antibiotic (see also Penicillin G). Reproduction studies conducted in mice (200 mg/kg), rats (500 or 1000 mg/kg), and monkeys (500 mg/kg) observed no fetal harm (1).

The drug crosses the placenta and distributes to most fetal tissues (2,3). After a 4-g IM dose, mean peak concentrations in cord and maternal serums at 2 hours were similar. Amniotic fluid levels averaged 7%11% of maternal peak concentrations.

No published reports linking the use of carbenicillin with congenital defects have been located. The Collaborative Perinatal Project monitored 50,282 mother-child pairs, 3,546 of whom had documented 1st trimester exposure to penicillin derivatives (4, pp. 297313). For use anytime during pregnancy, 7,171 exposures were recorded (4, pp. 435). In neither group was evidence found to suggest a relationship to large categories of major or minor malformations or to individual defects.

In a surveillance study of Michigan Medicaid recipients involving 229,101 completed pregnancies conducted between 1985 and 1992, 31 newborns had been exposed to carbenicillin during the 1st trimester (F. Rosa, personal communication, FDA, 1993). A total of five (16.1%) major birth defects were observed (one expected), one of which was a cardiovascular defect (0.5 expected). No anomalies were observed in five other categories of defects (oral clefts, spina bifida, polydactyly, limb reduction defects, and hypospadias) for which specific data were available. The number of exposures is too small to draw any conclusions.

Breast Feeding Summary

No reports describing the use of carbenicillin during lactation have been located. Because other penicillins are excreted in milk in low concentrations (e.g., see Ampicillin and Penicillin G) the presence of carbenicillin should also be expected. Although adverse effects from other penicillins in breast milk are rare, three potential problems exist for the nursing infant: modification of bowel flora, direct effects on the infant (e.g., allergic response), and interference with the interpretation of culture results if a fever workup is required.

References

1. Product information. Geocillin. Pfizer, 2000.
2. Biro L, Ivan E, Elek E, Arr M. Data on the tissue concentration of antibiotics in man. Tissue concentrations of semi-synthetic penicillins in the fetus. Int Z Pharmakol Ther Toxikol 1970;4:3214.
3. Elek E, Ivan E, Arr M. Passage of penicillins from mother to foetus in humans. Int J Clin Pharmacol Ther Toxicol 1972;6:2238.
4. Heinonen OP, Slone D, Shapiro S. Birth Defects and Drugs in Pregnancy. Littleton, MA:Publishing Sciences Group, 1977.