Elvucitabine is a deoxycytidine analogue with activity against HIV resistant to several other nucleoside analogues, including zidovudine and lamivudine. This is partly because of high intracellular levels of its triphosphate metabolite reached in cells. Clinical trials of elvucitabine are on hold, because it has shown bone marrow suppression in some patients, with CD4+ cell numbers dropping as early as two days after initiation of dosing.