Medication Guide App

Flucytosine Dosage

This dosage information may not include all the information needed to use Flucytosine safely and effectively. See additional information for Flucytosine.

The information at Drugs.com is not a substitute for medical advice. ALWAYS consult your doctor or pharmacist.

Usual Adult Dose for Candida Urinary Tract Infection

Serious infections due to susceptible strains of Candida and/or Cryptococcus (including septicemia, endocarditis, urinary system infections, meningitis, and pulmonary infections): 50 to 150 mg/kg/day orally in divided doses every 6 hours (in conjunction with amphotericin B)

Alternatively, the Infectious Diseases Society of America (IDSA) recommends a dosage of 100 mg/kg/day orally in 4 divided doses (in conjunction with amphotericin B or fluconazole).

Usual Adult Dose for Candidemia

Serious infections due to susceptible strains of Candida and/or Cryptococcus (including septicemia, endocarditis, urinary system infections, meningitis, and pulmonary infections): 50 to 150 mg/kg/day orally in divided doses every 6 hours (in conjunction with amphotericin B)

Alternatively, the Infectious Diseases Society of America (IDSA) recommends a dosage of 100 mg/kg/day orally in 4 divided doses (in conjunction with amphotericin B or fluconazole).

Usual Adult Dose for Cryptococcal Meningitis - Immunocompetent Host

Serious infections due to susceptible strains of Candida and/or Cryptococcus (including septicemia, endocarditis, urinary system infections, meningitis, and pulmonary infections): 50 to 150 mg/kg/day orally in divided doses every 6 hours (in conjunction with amphotericin B)

Alternatively, the Infectious Diseases Society of America (IDSA) recommends a dosage of 100 mg/kg/day orally in 4 divided doses (in conjunction with amphotericin B or fluconazole).

Usual Adult Dose for Cryptococcal Meningitis - Immunosuppressed Host

Serious infections due to susceptible strains of Candida and/or Cryptococcus (including septicemia, endocarditis, urinary system infections, meningitis, and pulmonary infections): 50 to 150 mg/kg/day orally in divided doses every 6 hours (in conjunction with amphotericin B)

Alternatively, the Infectious Diseases Society of America (IDSA) recommends a dosage of 100 mg/kg/day orally in 4 divided doses (in conjunction with amphotericin B or fluconazole).

Usual Adult Dose for Cryptococcosis

Serious infections due to susceptible strains of Candida and/or Cryptococcus (including septicemia, endocarditis, urinary system infections, meningitis, and pulmonary infections): 50 to 150 mg/kg/day orally in divided doses every 6 hours (in conjunction with amphotericin B)

Alternatively, the Infectious Diseases Society of America (IDSA) recommends a dosage of 100 mg/kg/day orally in 4 divided doses (in conjunction with amphotericin B or fluconazole).

Usual Adult Dose for Fungal Endocarditis

Serious infections due to susceptible strains of Candida and/or Cryptococcus (including septicemia, endocarditis, urinary system infections, meningitis, and pulmonary infections): 50 to 150 mg/kg/day orally in divided doses every 6 hours (in conjunction with amphotericin B)

Alternatively, the Infectious Diseases Society of America (IDSA) recommends a dosage of 100 mg/kg/day orally in 4 divided doses (in conjunction with amphotericin B or fluconazole).

Usual Adult Dose for Systemic Fungal Infection

Serious infections due to susceptible strains of Candida and/or Cryptococcus (including septicemia, endocarditis, urinary system infections, meningitis, and pulmonary infections): 50 to 150 mg/kg/day orally in divided doses every 6 hours (in conjunction with amphotericin B)

Alternatively, the Infectious Diseases Society of America (IDSA) recommends a dosage of 100 mg/kg/day orally in 4 divided doses (in conjunction with amphotericin B or fluconazole).

Usual Pediatric Dose for Systemic Fungal Infection

Serious infections due to susceptible strains of Candida and/or Cryptococcus (including septicemia, endocarditis, urinary system infections, meningitis, and pulmonary infections):
Less than 1 month: 25 to 100 mg/kg/day orally in divided doses every 12 to 24 hours (in conjunction with amphotericin B) has been suggested
1 month to 18 years: 50 to 150 mg/kg/day orally in divided doses every 6 hours (in conjunction with amphotericin B) has been suggested

Renal Dose Adjustments

CrCl 20 to 40 mL/min: 12.5 to 37.5 mg/kg orally every 12 hours
CrCl 10 to 20 mL/min: 12.5 to 37.5 mg/kg orally every 24 hours
CrCl less than 10 mL/min: 12.5 to 37.5 mg/kg orally every 24 to 48 hours or longer, depending on serum drug concentrations

Liver Dose Adjustments

Data not available

Precautions

Use flucytosine with extreme caution in patients with impaired renal function. Since flucytosine is excreted primarily by the kidneys, renal impairment may lead to accumulation of the drug. Flucytosine levels should be monitored to determine the adequacy of renal excretion in such patients. Dosage adjustments should be made in patients with renal impairment to prevent progressive accumulation of active drug. Close monitoring of renal status of all patients is essential.

Flucytosine must be given with extreme caution in patients with bone marrow depression. Patients may be more prone to bone marrow suppression if they have a hematologic disease, are being treated with radiation or other drugs which depress bone marrow, or have a history of treatment with such drugs or radiation. Bone marrow toxicity can be irreversible and may lead to death in immunosuppressed patients. Close monitoring of hematologic status of all patients is essential.

Peak blood concentrations of flucytosine should not exceed 100 mcg/mL. Prolonged serum levels in excess of 100 mcg/mL may be associated with an increased risk of toxicity, especially gastrointestinal (diarrhea, nausea, vomiting), hematologic (leukopenia, thrombocytopenia), and hepatic (hepatitis).

Close monitoring of hepatic (alkaline phosphatase, SGOT, and SGPT) and electrolytes status of all patients is essential.

The safety and efficacy of flucytosine have not been systematically studied in pediatric patients. A small number of neonates have been treated with 25 to 200 mg/kg/day of flucytosine, with and without the addition of amphotericin B therapy, for systemic candidiasis. No unexpected side effects were reported in these patients. It should be noted, however, that hypokalemia and acidemia were observed in one patient who received flucytosine in combination with amphotericin B, and anemia was observed in a second patient who received flucytosine alone. Transient thrombocytopenia was observed in two additional patients, one of whom also received amphotericin B therapy.

Dialysis

Patients undergoing hemodialysis every 48 to 72 hours: 20 to 50 mg/kg orally following dialysis session

Flucytosine is dialyzable (50% to 100%). The dose should be given post hemodialysis.

Other Comments

Nausea or vomiting may be reduced or avoided if the capsules are given a few at a time over a 15 minute period.

Flucytosine should be used in conjunction with amphotericin B for the treatment of systemic candidiasis and cryptococcosis due to the emergence of resistance to flucytosine. In patients who cannot receive amphotericin B, oral fluconazole may be administered with flucytosine.

The duration of therapy depends on the nature and severity of the infection.

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