45-year-old man is placed on an antifungal agent for systemic infection. He is noted to have decreased serum leukocyte and platelet counts. Bone marrow suppression is a common adverse effect of which of the following drugs

ANTIMETABOLITE Flucytosine (5-FC) Mech of action:- It is a pyrimidine antimetabolite which is inactive as such. After uptake into fungal cells, it is conveed into 5-fluorouracil and then to 5-fluorodeoxyuridylic acid which is an inhibitor of thymidylate synthesis. Thymidylic acid is a component of DNA. 5-FC is a narrow spectrum fungistatic, active against Cryptococcus neoformans, Torula, Chromoblastomyces; and a few strains of Candida. Adverse effects:- Toxicity of 5-FC consists of dose-dependent bone marrow depression and gastrointestinal disturbances, paicularly enteritis and diarrhoea. Liver dysfunction is mild and reversible. Ref:- kd tripathi; pg num:-791