Ancobon - General Information
A fluorinated cytosine analog that is used as an antifungal agent.
Pharmacology of Ancobon
Ancobon is an antimetabolite that acts as an antifungal agent with in vitro and in vivo activity against Candida and Cryptococcus. Ancobon 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.
Ancobon for patients
Bone marrow toxicity can cause anemia, leukopenia, pancytopenia, thrombocytopenia and, rarely, agranulocytosis and eosinophilia. Other side effects can be nausea, vomiting, anorexia, bloating, diarrhea, and, rarely, bowel perforation. Reversible elevations in liver enzymes have been reported. Occasionally, rashes may be a side effect. Some side effects that have only been seen very rarely are confusion, hallucinations, headaches, sedation, vertigo and liver enlargement.There has also been a case of severe allergic-type reaction to the drug in at least one person with AIDS. This type of reaction is called anaphylaxis.
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.
5-Flucytosine should not be used in patients with a known hypersensitivity to the drug.
Additional information about Ancobon
Ancobon Indication: 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).
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 5-fluorouracil. Ancobon 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.
Drug Interactions: Not Available
Food Interactions: Not Available
Generic Name: Flucytosine
Synonyms: 5-FC; 5-Fluorocystosine; 5-Fluorocytosin; 5-Fluorocytosine; 5-Flurocytosine; Flucytosin; Fluocytosine; Fluorcytosine
Drug Category: Antimetabolites; Antifungals
Drug Type: Small Molecule; Approved
Other Brand Names containing Flucytosine: Ancobon; Ancotil;
Absorption: Rapidly and virtually completely absorbed following oral administration. Bioavailability 78% to 89%.
Toxicity (Overdose): Oral, rat: LD50 = >15 gm/kg.
Protein Binding: 28-31%
Biotransformation: Flucytosine is deaminated, possibly by gut bacteria or by the fungal targets, to 5-fluorouracil, the active metabolite.
Half Life: 2.4 to 4.8 hours.
Dosage Forms of Ancobon: Capsule Oral
Chemical IUPAC Name: 4-amino-5-fluoro-3H-pyrimidin-2-one
Chemical Formula: C4H4FN3O
Flucytosine on Wikipedia: http://en.wikipedia.org/wiki/Flucytosine
Organisms Affected: Yeast and other fungi