Flucytosine (5-fluorocytosine) is an antimetabolite antifungal drug. It works by being taken up by fungal cells and converted into 5-fluorouracil, which inhibits DNA and RNA synthesis, thereby disrupting fungal cell growth. Fluconazole, itraconazole, and ketoconazole are azole antifungals that primarily inhibit ergosterol synthesis, a different mechanism of action compared to antimetabolites.