A dideoxynucleoside compound in which the 3'-hydroxy group on the sugar moiety has been replaced by a hydrogen. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. The compound is a potent inhibitor of HIV replication at low concentrations, acting as a chain-terminator of viral DNA by binding to reverse transcriptase. Its principal toxic side effect is axonal degeneration resulting in peripheral neuropathy.

A synthetic dideoxynucleoside. After intracellular phosphorylation to its active metabolite, zalcitabine preferentially inhibits the gamma form of DNA polymerase present in tumor cell mitochondria, resulting in the inhibition of tumor cell mitochondrial DNA replication and tumor cell death. (NCI04)

(2'3' dideoxycytidine) Cytidine analog which inhibits reverse transcriptase and has potential efficacy against AIDS.