 In 1974 zidovudine was reported to have activity against retroviruses and was subsequently re-screened as an antiviral when the AIDS epidemic hit Western societies during the
mid 1980s.However, zidovudine is relatively toxic since it is converted into the
triphosphate by the cellular enzymes and therefore it is activated in uninfected cells.Dideoxynucleosides are analogues of nucleoside where the sugar ring lacks both 2´ and 3´-hydroxyl groups.