5-Fluorocystosine

5-Fluorocystosine Uses, Dosage, Side Effects, Food Interaction and all others data.

A fluorinated cytosine analog that is used as an antifungal agent.

5-Fluorocystosine is an antimetabolite that acts as an antifungal agent with in vitro and in vivo activity against Candida and Cryptococcus. 5-Fluorocystosine enters the fungal cell via cytosine permease; thus, flucytosine is metabolized to 5-fluorouracil within fungal organisms. The 5-fluorouracil is extensively incorporated into fungal RNA and inhibits synthesis of both DNA and RNA. The result is unbalanced growth and death of the fungal organism. Antifungal synergism between Ancobon and polyene antibiotics, particularly amphotericin B, has been reported.

Trade Name 5-Fluorocystosine
Availability Prescription only
Generic Flucytosine
Flucytosine Other Names 5-FC, 5-Fluorocystosine, 5-Fluorocytosine, flucytosina, Flucytosine, Flucytosinum
Related Drugs fluconazole, Diflucan, itraconazole, amphotericin b, voriconazole, posaconazole, Sporanox, Vfend, Fungizone, Ancobon
Type
Formula C4H4FN3O
Weight Average: 129.0925
Monoisotopic: 129.03383997
Protein binding

28-31%

Groups Approved, Investigational
Therapeutic Class
Manufacturer
Available Country
Last Updated: September 19, 2023 at 7:00 am
5-Fluorocystosine
5-Fluorocystosine

Uses

5-Fluorocystosine is an antifungal indicated only to treat severe infections throughout the body caused by susceptible strains of Candida or Cryptococcus.

For the treatment (in combination with amphotericin B) of serious infections caused by susceptible strains of Candida (septicemia, endocarditis and urinary system infections) and/or Cryptococcus (meningitis and pulmonary infections).

5-Fluorocystosine is also used to associated treatment for these conditions: Bloodstream Infections, Candidiasis, Candidiasis, Systemic, Cryptococcal infections, Fungal endocarditis, Infections, Fungal, Meningitis, Fungal, Urinary tract infection fungal, Disseminated Cryptococcosis

How 5-Fluorocystosine works

Although the exact mode of action is unknown, it has been proposed that flucytosine acts directly on fungal organisms by competitive inhibition of purine and pyrimidine uptake and indirectly by intracellular metabolism to 5-fluorouracil. 5-Fluorocystosine enters the fungal cell via cytosine permease; thus, flucytosine is metabolized to 5-fluorouracil within fungal organisms. The 5-fluorouracil is extensively incorporated into fungal RNA and inhibits synthesis of both DNA and RNA. The result is unbalanced growth and death of the fungal organism. It also appears to be an inhibitor of fungal thymidylate synthase.

Toxicity

Oral, rat: LD50 = >15 gm/kg.

Food Interaction

No interactions found.

Elimination Route

Rapidly and virtually completely absorbed following oral administration. Bioavailability 78% to 89%.

Half Life

2.4 to 4.8 hours.

Elimination Route

5-Fluorocystosine is excreted via the kidneys by means of glomerular filtration without significant tubular reabsorption. A small portion of the dose is excreted in the feces.

Innovators Monograph

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