flucytosine: profile and news

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Other information

Indication
For treatment of (in combination with Amphotericin B) meningitis, endophthalmitis and pylelonephritis

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

Mechanism Of Action
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 monophosphate, a noncompetitive inhibitor of the fungal thymidylate synthetase which interferes with DNA synthesis. Flucytosine interrupts nucleic acid and protein synthesis. The cells of the host do not convert large quantities of flucytosine to fluorouracil, accounting for the selective toxicity of the compound against fungi.

Drug Category
Antimetabolites; Antifungals; ATC:D01AE21; ATC:J02AX01

Brand Names/Synonyms
Ancobon; Ancotil; Flucytosin; Flucytosine; Fluocytosine; Fluorcytosine

Dosage Forms
Not Available

Absorption
Rapidly and completely absorbed, bioavailability is 78-90%

Interactions
Interactions for 5-Flucytosine: Cytosine arabinoside, a cytostatic agent, has been reported to inactivate the antifungal activity of flucytosine by competitive inhibition. Drugs which impair glomerular filtration may prolong the biological half-life of flucytosine. Drug/Laboratory Test Interactions: Measurement of serum creatinine levels should be determined by the Jaffe reaction, since Ancobon does not interfere with the determination of creatinine values by this method. Most automated equipment for measurement of creatinine makes use of the Jaffe reaction.

Chemical IUPAC Name
4-amino-5-fluoro-3H-pyrimidin-2-one

Chemical Formula
C4H4FN3O

Half Life
2.4 and 4.8 hours

Drug Type
Approved Drug

# Accession No
APRD00299

CAS Registry Number
2022-85-7