Zalcitabine

Zalcitabine is a nucleoside reverse transcriptase inhibitor and a deoxycytidine analog. After entering the cell, it is sequentially phosphorylated by host cell kinases into zalcitabine-5'-triphosphate, its active form. Zalcitabine-5'-triphosphate competes with dCTP and is mistakenly incorporated into elongating viral DNA by HIV reverse transcriptase. Because zalcitabine lacks a 3'-OH group, its incorporation results in termination of viral DNA synthesis.