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Research Area
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Description
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Infection |
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Biological Activity
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Description
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Flucytosine (5-Fluorocytosine, 5-FC, Ancobon) is an antifungal drug with IC50 of 0.12 μg/mL in C. albicans. |
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Targets
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Fungal cells |
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IC50 |
0.12 μg/mL for C. albicans [ |
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In Vitro
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Flucytosine inhibits the growth of C. neoformans in Sabouraud's dextrose broth at concentrations ≥ 1.25 mg/L, and Flucytosine of 50 mg/L causes a ~50% reduction in colony-forming unit (cfu)\ in the J774.16 killing assay with viability of J774.16 cells not affected measured by trypan blue exclusion. The combination of Flucytosine and IgGl monoclonal antibody to Cryptococcus neoformans capsular glucuronoxylomannan is more effective in reducing the numbers of C. neoformans colony-forming units in vitro with J774.16 murine macrophage-like cells than either agent alone. [2] The efficacy of Flucytosine (5FC) in combination with amphotericin B (AB) and fluconazole (FCZ) is studied against 35 yeast isolates, of which the 5FC-FCZ combination is antagonistic against Candida species, but for some Candida isolates synergism is found.[3] |
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In Vivo
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Administration of Flucytosine in combination with monoclonal antibody 2H1 to A/JCr mice infected with C. neoformans significantly reduces lung but not brain cfu, which is more effective than either agent alone. [2] The combination of intravenous Flucytosine in 0.9% saline (NaCl) and amphotericin B (AmB) provides synergistic antifungal activity and is associated with a lower incidence of nephrotoxicity than with AmB treatment alone. Infusion of Flucytosine (5-10 mg/kg/min) dissolved in 5% glucose into the renal artery of an in situ perfused kidney for 15 minutes increases renal blood flow (RBF) in the rat, and the renal vasodilatation persists for the duration of the Flucytosine infusion, with a maximal increase of 2.5±0.7 mL/min. [4] |
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Clinical Trials
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Clinical trail completed in evaluating the effectiveness and safety of Amphotericin B plus Flucytosine (5-Fluorocytosine) compared to Amphotericin B alone for a first episode of acute cryptococcal meningitis in AIDS patients, and comparing the effectiveness and safety of Fluconazole versus Itraconazole. |
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Features
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Flucytosine is first synthesized in 1957 but its antifungal properties discovered in 1964. |
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Protocol
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Kinase Assay
[1]
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| Microdilution method |
The culture media used are RPMI 1640 with glutamine, without bicarbonate and phenol red, buffered with morpholinopropanesulfonic acid (MOPS) (0.165 M, pH 7.0). Two-fold serial dilutions of Flucytosine (0.06-64 μg/mL) are prepared and dispensed in 50 uL aliquot, in flat-bottom 96-well assay plates which are kept frozen at -70 °C in sealed plastic bags until used. The inoculum is prepared spectrophotometrically and standardized to a concentration of 1.0-5.0 × 103 cfu per mL. A 50 μL volume of this suspension is used to inoculate each well containing 50 μL of the double concentration of Flucytosine to be tested. Once inoculated, each well therefore contains 100 μL of broth favoured over 200 μL to facilitate the agitation of the plates prior to spectrophotometric reading. After an incubation period of 24 and 48 hours at 35 °C, the plates are agitated for 3 minutes at 900 r.p.m. with a shaker and the optical density of the growth in each well is determined with the use of an automatic plate reader set at 495 nm. The inhibitory concentration of IC50 is computed mathematically. |
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Cell Assay
[2]
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| Cell Lines |
J774.16 murine macrophage-like cell line |
| Concentrations |
Dissolved in PBS, final concentration 50 mg/L |
| Incubation Time |
24 hours |
| Methods |
J774.16 murine macrophage-like cells plated on 96-well tissue culture plates are incubated with 500 u/mL murine recombinant gamma-interferon overnight at 37 °C. The medium is then replaced with fresh medium containing gamma-interferon 500 μ/mL, LPS 3 mg/L, C. neoformans cells 1.6 × 104/well and Flucytosine 50 mg/L. Plates are incubated for 24 hours at 37 °C. Cell supernatants are collected and cells lysed by adding 0.1 mL sterile distilled water to each well, incubating at room temperature for 30 minutes, and then aspirating and ejecting the lysate with a pipette several times to complete cell disruption. Wells are rinsed with PBS (0.1 mL) and the cell supernatant, and lysate and rinse from each well are pooled, vortexed, diluted 1:50, vortexed again and spread on Sabouraud's dextrose agar for the cfu determination |
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Animal Study
[4]
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| Animal Models |
Male Sprague-Dawley rats |
| Formulation |
Dissolved in 5% glucose |
| Doses |
5 mg/kg/min |
| Administration |
In situ renal perfusion at a rate of 0.13 mL/min |
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References |
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[1] St-Germain G. Mycoses, 2001, 44(1-2), 37-45.
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[2] Feldmesser M, et al. J Antimicrob Chemother, 1996, 37(3), 617-622.
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[3] Te Dorsthorst DT, et al. Antimicrob Agents Chemother, 2002, 46(9), 2982-2989.
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[4] Heidemann HT, et al. Antimicrob Agents Chemother, 1992, 36(12), 2670-2675.
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