Use In Pregnancy and Lactaion
Pregnancy
This drug should be used during pregnancy only if the benefit
outweighs the risk to the fetus. AU TGA pregnancy category: B3 US FDA pregnancy
category: Not assigned. Risk summary: Malformative risk with use of this drug
in pregnant women is unlikely. Comments: A pregnancy exposure registry is
available.
Animal studies (high-dose) have revealed evidence of embryonic
and fetal toxicity, including developmental toxicity, fetal anasarca, skeletal
malformations, and increased incidence of stillbirth. Placental transfer has
been observed in humans. There are no controlled data in human pregnancy;
however, based on observed outcomes (more than 800 after first-trimester
exposure and more than 1000 after second-/third-trimester exposure), the
malformative risk is unlikely in humans. To monitor maternal-fetal outcome of
pregnant women exposed to antiretroviral therapy, an Antiretroviral Pregnancy
Registry (APR) has been established. Healthcare providers are encouraged to
prospectively register patients. For additional information: apregistry.com The
APR has received prospective reports of over 2000 exposures to this drug (over
900 exposed in the first trimester) resulting in live births; there was no
difference between abacavir and overall birth defects compared with the
background birth defect rate of 2.7% in the reference population. The
prevalence of defects in the first trimester was 3% for abacavir. No increased
risk of major birth defects observed for this drug compared to background rate.
AU TGA pregnancy category B3: Drugs which have been taken by only a limited
number of pregnant women and women of childbearing age, without an increase in
the frequency of malformation or other direct or indirect harmful effects on
the human fetus having been observed. Studies in animals have shown evidence of
an increased occurrence of fetal damage, the significance of which is
considered uncertain in humans. US FDA pregnancy category Not Assigned: The US
FDA has amended the pregnancy labeling rule for prescription drug products to
require labeling that includes a summary of risk, a discussion of the data
supporting that summary, and relevant information to help health care providers
make prescribing decision and counsel women about the use of drugs during
pregnancy. Pregnancy categories A, B, C, D, and X are being phased out.
Lactation
Breast milk from 15 women and blood samples from 9 of their
partially or exclusively breastfed infants were collected about 1 month
postpartum; the mothers were using abacavir 300 mg twice a day (with lamivudine
and zidovudine). Breast milk was obtained right before a dose; whole breast
milk abacavir levels averaged 0.057 mg/L (about 85% of maternal blood levels).
Infant blood was obtained 11 to 18 hours after the last maternal dose and about
1 hour (range: 6 minutes to 35 hours) after the last breastfeeding; plasma drug
levels were undetectable (less than 16 mcg/L) in 8 of 9 infants.
Breastfeeding is not recommended during use of this drug; if
replacement feeding is not an option, a different drug may be preferred.
Excreted into human milk: Yes Comments: -The effects in the nursing infant are
unknown. -The US CDC, American Academy of Pediatrics, and manufacturer advise
HIV-infected women not to breastfeed to avoid postnatal transmission of HIV to
a child who may not yet be infected. -Local guidelines should be consulted if
replacement feeding is not an option.
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