Flucytosine—a synthetic antimetabolite effective in vitro against most strains of Cryptococcus neoformans, Candida albicans, and Torulopsis glabrata—is, in contrast to amphotericin B, well absorbed from the gastrointestinal tract, passes readily into cerebrospinal fluid from blood, and, in the absence of renal failure, appears to cause little toxicity. Nevertheless, there are problems that have prevented identification of the precise role of this drug in the treatment of mycotic infections.
With regard to sensitivities of various fungi to flucytosine, a large body of in vitro data has accumulated, but their interpretation is hampered by the lack of a standardized method for the determination of sensitivity of fungi to this drug. This means that results of sensitivity testing from different laboratories may not be comparable.1,2 For example, the frequency of sensitivity of pretreatment C albicans isolates has been reported to be in the 90% to 95% range3 and the 50%
Krick JA, Remington JS. Treatment of Fungal Infections. Arch Intern Med. 1975;135(2):344–346. doi:10.1001/archinte.1975.00330020148021