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Recommendations for Use of Antiretroviral Drugs in Pregnant HIV-1-Infected Women for Maternal Health and Interventions to Reduce Perinatal HIV Transmission in the United States

Appendix B: Supplement: Safety and Toxicity of Individual Antiretroviral Agents in Pregnancy

Nucleoside and Nucleotide Analogue Reverse Transcriptase Inhibitors

Glossary of Terms for Supplement

Carcinogenic: Producing or tending to produce cancer
Some agents, such as certain chemicals or forms of radiation, are both mutagenic and clastogenic.
Genetic mutations and/or chromosomal damage can contribute to cancer formation.

Clastogenic: Causing disruption of or breakages in chromosomes
Genotoxic: Damaging to genetic material such as DNA and chromosomes
Mutagenic: Inducing or capable of inducing genetic mutation
Teratogenic: Interfering with fetal development and resulting in birth defects

Six nucleoside analogue reverse transcriptase inhibitors (nucleoside NRTIs) and one nucleotide reverse transcriptase inhibitor (nucleotide NRTI) are currently approved; zalcitabine is no longer available in the United States. Data are available from clinical trials in human pregnancy for the nucleoside NRTIs zidovudine, abacavir, lamivudine, didanosine, emtricitabine, and stavudine and the nucleotide NRTI tenofovir. The nucleoside analogue drugs require three intracellular phosphorylation steps to form the triphosphate nucleoside, which is the active drug moiety. Tenofovir, an acyclic nucleotide analogue drug, contains a monophosphate component attached to the adenine base and, hence, requires only two phosphorylation steps to form the active moiety.

For information regarding the nucleoside analogue drug class and potential mitochondrial toxicity in pregnancy and to the infant, see NRTI Drugs and Mitochondrial Toxicity

Abacavir (Ziagen, ABC)
Didanosine (Videx, ddI)
Emtricitabine (Emtriva, FTC)
Lamivudine (Epivir, 3TC)
Stavudine (Zerit, d4T)
Tenofovir disoproxil fumarate (Viread, TDF)
Zalcitabine (HIVID, ddC) 
Zidovudine (Retrovir, AZT, ZDV)