Pregnancy: As a general rule, when deciding to use antiretroviral agents for the treatment HIV infection in pregnant women and consequently for reducing the risk of HIV vertical transmission to the newborn, both animal data as well as clinical experience in pregnant women should be taken into account.
Animal studies have shown toxicity to the developing embryo and foetus in rats, but not in rabbits (see Pharmacology: Toxicology: Preclinical safety data under Actions). Abacavir has been shown to be carcinogenic in animal models (see Pharmacology: Toxicology: Preclinical safety data under Actions). Clinical relevance in human of these data is unknown. Placental transfer of abacavir and/or its related metabolites has been shown to occur in human.
In pregnant women, more than 800 outcomes after first trimester exposure and more than 1000 outcomes after second and third trimester exposure indicate no malformative and foetal/neonatal effect of abacavir. The malformative risk is unlikely in humans based on those data.
Mitochondrial dysfunction: Nucleoside and nucleotide analogues have been demonstrated in vitro and in vivo to cause a variable degree of mitochondrial damage. There have been reports of mitochondrial dysfunction in HIV-negative infants exposed in utero and/or post-natally to nucleoside analogues (see Mitochondrial dysfunction following exposure in utero under Precautions).
Breast-feeding: Abacavir and its metabolites are excreted into the milk of lactating rats. Abacavir is also excreted into human milk. There are no data available on the safety of abacavir when administered to babies less than three months old. It is recommended that HIV infected women do not breast-feed their infants under any circumstances in order to avoid transmission of HIV.
Fertility: Studies in animals showed that abacavir had no effect on fertility (see Pharmacology: Toxicology: Preclinical safety data under Actions).