Anti-infective
PREGNANCY RECOMMENDATION: Compatible—Maternal Benefit >> Embryo/Fetal Risk
BREASTFEEDING RECOMMENDATION: No Human Data—Potential Toxicity
PREGNANCY SUMMARY
No reports describing the use of linezolid during human pregnancy have been located. Because of the lack of human pregnancy data, other antibiotics with this experience should be used if possible. If no other alternatives are available and linezolid must be used, the maternal benefit appears to outweigh the unknown fetal risk.
FETAL RISK SUMMARY
Linezolid is a synthetic, oxalodinone class, antibacterial agent that is indicated for the treatment of gram-positive bacteria, including vancomycin-resistant enterococcus (VRE). It is available in both oral and IV formulations.
Reproduction studies have been conducted in pregnant mice and rats (1). No evidence of teratogenicity was seen in mice and rats at doses that were 4 and 1 times the expected human exposure based on AUC (EHE), respectively. However, in mice, embryo and fetal toxicity (embryo death, including total litter loss, decreased fetal weight, and an increased incidence of costal cartilage fusion) and maternal toxicity (clinical signs and reduced weight gain) were seen at this dose. In pregnant rats, doses 0.13 and 0.64 times the EHE resulted in slight fetal toxicity (reduced fetal weight and ossification of sternebrae). The higher dose (0.64 times the EHE) caused slight maternal toxicity consisting of reduced body weight gain. When this dose was given during pregnancy and lactation, pup survival was decreased on postnatal days 1 to 4. In addition, when surviving pups reached maturity and were mated, they had decreased fertility as evidenced by an increase in preimplantation loss (1).
It is not known if linezolid crosses the human placenta. The molecular weight (about 337) is low enough that transfer to the fetus should be expected.
BREASTFEEDING SUMMARY
No reports describing the use of linezolid during human lactation have been located. The molecular weight (about 337) is low enough that excretion into breast milk should be expected. The effects of this exposure on a nursing infant are unknown, but myelosuppression and reversible thrombocytopenia are potential complications. Women taking linezolid should probably not breastfeed.
Reference
1.Product information. Zyvox. Pharmacia & Upjohn, 2001.