Name: Flucytosine (5-Fluorocytosine)
Brand: Selleck Chemicals
SKU: S1666
Availability: InStock
Rating: 5 (3 reviews)

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Quality Control

Batch: Purity: 99.93%

99.93

Related Targets	Integrase Bacterial Antibiotics Anti-infection Antiviral COVID-19 Parasite Reverse Transcriptase HIV HCV Protease
Other Fungal Inhibitors	Cycloheximide Tolnaftate Manogepix (E1210) Amorolfine HCl Isavuconazole Juglone Bifonazole Thimerosal Pseudolaric Acid B Butylparaben

Solubility

In vitro
Batch:

DMSO : 13 mg/mL (100.7 mM)
(Moisture-contaminated DMSO may reduce solubility. Use fresh, anhydrous DMSO.)

Water : 7 mg/mL

Ethanol : Insoluble

Molarity Calculator

Mass	Concentration	Volume	Molecular Weight
Mass value Mass unit	Concentration value Concentration unit	Volume value Volume unit	Molecular weight (g/mol)

Dilution Calculator Molecular Weight Calculator

In vivo batch selection In vivo Batch:
Homogeneous suspension	CMC-NA	≥5mg/ml	Taking the 1 mL working solution as an example, add 5 mg of this product to 1 ml of CMC-Na solution, mix evenly to obtain a homogeneous suspension with a final concentration of 5 mg/ml.
Homogeneous suspension	0.5% methylcellulose 1 0.2% Tween 80 Validated by Selleck labs. Should you need adjustments to this formulation, contact our sales team for custom testing.	5.000mg/ml (38.73mM)	Taking the 1 mL working solution as an example, take 5 mg of this product and add it to 1 ml of 0.5% methylcellulose+0.2% Tween 80 clear solution, and mix evenly to form a uniform suspension. The mixed solution should be used immediately for optimal results.
Homogeneous suspension	CMC-NA	≥5mg/ml	Taking the 1 mL working solution as an example, add 5 mg of this product to 1 ml of CMC-Na solution, mix evenly to obtain a homogeneous suspension with a final concentration of 5 mg/ml.
Homogeneous suspension	CMC-NA	≥5mg/ml	Taking the 1 mL working solution as an example, add 5 mg of this product to 1 ml of CMC-Na solution, mix evenly to obtain a homogeneous suspension with a final concentration of 5 mg/ml.
Homogeneous suspension	CMC-NA	≥5mg/ml	Taking the 1 mL working solution as an example, add 5 mg of this product to 1 ml of CMC-Na solution, mix evenly to obtain a homogeneous suspension with a final concentration of 5 mg/ml.

In vivo Formulation Calculator (Clear solution)

Step 1: Enter information below (Recommended: An additional animal making an allowance for loss during the experiment)

Dosage: mg/kg

Average weight of animals: g

Dosing volume per animal: μL

Number of animals:

Step 2: Enter the in vivo formulation (This is only the calculator, not formulation. Please contact us first if there is no in vivo formulation at the solubility Section.)

% DMSO

%

% Tween 80

% ddH₂O

% DMSO

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%

Calculation results:

Working concentration: mg/ml;

Method for preparing DMSO master liquid: mg drug pre-dissolved in μL DMSO ( Master liquid concentration mg/mL, Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug. )

Method for preparing in vivo formulation: Take μL DMSO master liquid, next addμL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH₂O, mix and clarify.

Method for preparing in vivo formulation: Take μL DMSO master liquid, next add μL Corn oil, mix and clarify.

Note: 1. Please make sure the liquid is clear before adding the next solvent.
2. Be sure to add the solvent(s) in order. You must ensure that the solution obtained, in the previous addition, is a clear solution before proceeding to add the next solvent. Physical methods such
as vortex, ultrasound or hot water bath can be used to aid dissolving.

Chemical Information, Storage & Stability

Molecular Weight	129.09	Formula	C₄H₄FN₃O	Storage (From the date of receipt)	3 years-20°Cpowder
CAS No.	2022-85-7	Download SDF		Storage of Stock Solutions	1 year-80°Cin solvent 1 month-20°Cin solvent
Synonyms	5-FC, NSC 103805, Ro 2-9915			SMILES	C1=NC(=O)NC(=C1F)N

Read more about storage stability stock solution CAS number SMILES

Mechanism of Action

Features	First synthesized in 1957, and antifungal properties discovered in 1964.
In vitro	Flucytosine (5-Fluorocytosine) inhibits the growth of C. neoformans in Sabouraud's dextrose broth at concentrations ≥ 1.25 mg/L, and this compound at 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 it 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. The efficacy of 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.
Kinase Assay	Microdilution method
Kinase Assay	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 (5-Fluorocytosine) (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 this compound 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.
In vivo	Administration of Flucytosine (5-Fluorocytosine) 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. The combination of intravenous it 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 this compound (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 infusion.
References	[1] https://pubmed.ncbi.nlm.nih.gov/11398639/ [2] https://pubmed.ncbi.nlm.nih.gov/9182119/ [3] https://pubmed.ncbi.nlm.nih.gov/12183257/ [4] https://pubmed.ncbi.nlm.nih.gov/1482135/

Clinical Trial Information

(data from https://clinicaltrials.gov, updated on 2026-05-28)

NCT Number	Recruitment	Conditions	Sponsor/Collaborators	Start Date	Phases
NCT06264388	RECRUITING	High Grade Glioma; Anaplastic Astrocytoma	Ashish Shah	2024-05-01	PHASE2
NCT06666322	RECRUITING	Hiv; Cryptococcal Meningitis	David Boulware	2025-05-28	PHASE2; PHASE3
NCT06525389	NOT_YET_RECRUITING	Talaromycosis	Duke University	2026-09-01	PHASE3
NCT04105374	WITHDRAWN	Anaplastic Astrocytoma; Glioblastoma; Oligodendroglioma; Supratentorial Glioblastoma	NRG Oncology	2020-01-31	PHASE2; PHASE3
NCT06178627	UNKNOWN	Cryptococcal Meningitis; Antifungal Agents	Huashan Hospital	2023-08-13	PHASE4
NCT06414512	COMPLETED	Cryptococcal Meningitis	University of Minnesota	2024-04-09	PHASE2

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Flucytosine (5-Fluorocytosine) Fungal inhibitor

Chemical Structure

Molecular Weight: 129.09