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flucytosine; 5-fluorocytosine (Ancobin, 5-FC)

Tradename: Ancobin. Indications: 1) used in combination with amphotericin B in treatment of fungal meningitis 2) used in combination with susceptible fungal infections, generally Candida or Cryptococcus - candiduria 3) resistance develops rapidly when used alone Dosage: 50-150 mg/kg/day PO divided QID. Tabs: 250 & 500 mg. Dose adjustment in renal failure: creatinine clearance dose > 40 mL/min 50-100 mg/kg/day 20-39 mL/min* 25-50 mg/kg/day < 19 mL/min 12.5-25 mg/kg/day * same dose for continuous arteriovenous hemofiltration Pharmacokinetics: 1) well absorbed orally 2) well distributed to tissues, including CSF & eye 3) eliminated largely in the urine unchanged 4) elimination 1/2life is 6 hours (75-200 hours ESRD) Monitor: - therapeutic monitoring: - doses adjusted by laboratory parameters of hepatotoxicity, nephrotoxicity & myelotoxicity without measuring blood levels Adverse effects: 1) most common (1-10%) - anemia, hepatitis, jaundice, skin rash, leukopenia, thrombocytopenia, abdominal pain, diarrhea, loss of appetite, nausea/vomiting 2) uncommon (< 1%) - confusion, hallucinations, photosensitivity, dizziness drowsiness, headache, cardiac arrest, paresthesia, parkinsonism, psychosis, ataxia, temporary growth failure, hypoglycemia, hypokalemia, bone marrow suppression, elevated serum transaminases, hearing loss, respiratory arrest, renal toxicity Drug interactions: 1) cytarabine antagonizes the effects of flucytosine 2) amphotericin B in combination may increase flucytosine, increasing toxicity 3) antacids in combination decrease flucytosine activity; take 2 hours apart Mechanism of action: - deaminated by fungal cytosine deaminase to 5-fluorouracil which is fungicidal

Interactions

drug interactions

Related

5-fluorocytosine in body fluid 5-fluorocytosine in serum/plasma 5-fluorocytosine in urine 5-fluorouracil [5-FU] (Fluoroplex, Efudex, Adrucel, Carac)

General

antifungal agent cytosine

Properties

MISC-INFO: elimination route KIDNEY protein-binding 2-4% 1/2life 3-8 HOURS elimination by hemodialysis + pregnancy-category C safety in lactation -

Database Correlations

PUBCHEM correlations

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. Medical Knowledge Self Assessment Program (MKSAP) 11, American College of Physicians, Philadelphia 1998
  3. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  4. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998