Zeffix Use In Pregnancy & Lactation

Fertility: Reproductive studies in animals have shown no effect on male or female fertility.
Pregnancy: Lamivudine has been evaluated in the Antiretroviral Pregnancy Registry in over 11,000 women during pregnancy and postpartum. Less than 1% of these women have been treated for HBV, whereas the majority was treated for HIV at higher doses and with other concomitant HIV medications. Available human data from the Antiretroviral Pregnancy Registry do not show an increased risk of major birth defects for lamivudine compared to the background rate (see Pharmacology: Pharmacodynamics: Clinical Studies under Actions). However, there are no adequate and well-controlled trials in pregnant women and the safe use of lamivudine in human pregnancy has not been established.
Studies in humans have confirmed that ZEFFIX crosses the placenta.
Use in pregnancy should be considered only if the benefit outweighs the risk. Although the results of animal studies (see Pharmacology: Toxicology: Non-clinical Information under Actions) are not always predictive of human response, there was no evidence of teratogenicity in animals but, findings in the rabbit suggest a potential risk of early embryonic loss that was not observed in the rat. For patients who are being treated with ZEFFIX and subsequently become pregnant consideration should be given to the possibility of a recurrence of hepatitis on discontinuation of ZEFFIX (see Precautions).
Lactation: Following repeat oral administration of either 150 mg or 300 mg lamivudine twice daily, lamivudine was excreted in human breast milk (0.5 to 8.2 micrograms/ml) at similar concentrations to those found in serum. In other studies following repeat oral administration of 150 mg lamivudine twice daily the maternal plasma: breast milk ratio ranged between 0.6 and 3.3. Lamivudine median infant serum concentrations ranged between 18 and 28 ng/ml and were not detectable in one of the studies (assay sensitivity 7 ng/ml). The clinical relevance of this finding is unknown.
Data from animal studies in which neonatal rats received ZEFFIX at much higher concentrations via maternal milk suggest that the concentrations of lamivudine in human breast milk are unlikely to produce toxicity in breast-fed infants.
ZEFFIX should only be used in a nursing mother if the expected benefit justifies the potential risk to the infant. A decision must be made whether to discontinue breast-feeding or to discontinue/abstain from ZEFFIX therapy, taking into account the benefit of breast-feeding for the child and the benefit of therapy for the woman.