Flucytosine Dosage

Medically reviewed by Drugs.com. Last updated on Feb 28, 2025.

Usual Adult Dose for Candida Urinary Tract Infection

50 to 150 mg/kg/day orally in divided doses every 6 hours

Comments:

• This drug should be used in conjunction with amphotericin B for the treatment of systemic candidiasis and cryptococcosis (due to emerging resistance to this drug).
• Candida: Limited studies in pulmonary infections justify use of this drug.
• Cryptococcus: Limited trials in septicemias and urinary tract infections, but good responses reported.

Uses: For the treatment of serious infections due to susceptible strains of Candida (septicemia, endocarditis, urinary system infections, pulmonary infections) and/or Cryptococcus (meningitis, pulmonary infections, septicemia, urinary tract infections)

Infectious Diseases Society of America (IDSA) Recommendations: 100 mg/kg/day orally in 4 divided doses

Comments:

• In conjunction with amphotericin B (or fluconazole)
• Current guidelines should be consulted for additional information.

Usual Adult Dose for Candidemia

50 to 150 mg/kg/day orally in divided doses every 6 hours

Comments:

• This drug should be used in conjunction with amphotericin B for the treatment of systemic candidiasis and cryptococcosis (due to emerging resistance to this drug).
• Candida: Limited studies in pulmonary infections justify use of this drug.
• Cryptococcus: Limited trials in septicemias and urinary tract infections, but good responses reported.

Uses: For the treatment of serious infections due to susceptible strains of Candida (septicemia, endocarditis, urinary system infections, pulmonary infections) and/or Cryptococcus (meningitis, pulmonary infections, septicemia, urinary tract infections)

Infectious Diseases Society of America (IDSA) Recommendations: 100 mg/kg/day orally in 4 divided doses

Comments:

• In conjunction with amphotericin B (or fluconazole)
• Current guidelines should be consulted for additional information.

Usual Adult Dose for Cryptococcal Meningitis - Immunocompetent Host

50 to 150 mg/kg/day orally in divided doses every 6 hours

Comments:

• This drug should be used in conjunction with amphotericin B for the treatment of systemic candidiasis and cryptococcosis (due to emerging resistance to this drug).
• Candida: Limited studies in pulmonary infections justify use of this drug.
• Cryptococcus: Limited trials in septicemias and urinary tract infections, but good responses reported.

Uses: For the treatment of serious infections due to susceptible strains of Candida (septicemia, endocarditis, urinary system infections, pulmonary infections) and/or Cryptococcus (meningitis, pulmonary infections, septicemia, urinary tract infections)

Infectious Diseases Society of America (IDSA) Recommendations: 100 mg/kg/day orally in 4 divided doses

Comments:

• In conjunction with amphotericin B (or fluconazole)
• Current guidelines should be consulted for additional information.

Usual Adult Dose for Cryptococcal Meningitis - Immunosuppressed Host

50 to 150 mg/kg/day orally in divided doses every 6 hours

Comments:

• This drug should be used in conjunction with amphotericin B for the treatment of systemic candidiasis and cryptococcosis (due to emerging resistance to this drug).
• Candida: Limited studies in pulmonary infections justify use of this drug.
• Cryptococcus: Limited trials in septicemias and urinary tract infections, but good responses reported.

Uses: For the treatment of serious infections due to susceptible strains of Candida (septicemia, endocarditis, urinary system infections, pulmonary infections) and/or Cryptococcus (meningitis, pulmonary infections, septicemia, urinary tract infections)

Infectious Diseases Society of America (IDSA) Recommendations: 100 mg/kg/day orally in 4 divided doses

Comments:

• In conjunction with amphotericin B (or fluconazole)
• Current guidelines should be consulted for additional information.

Usual Adult Dose for Cryptococcosis

50 to 150 mg/kg/day orally in divided doses every 6 hours

Comments:

• This drug should be used in conjunction with amphotericin B for the treatment of systemic candidiasis and cryptococcosis (due to emerging resistance to this drug).
• Candida: Limited studies in pulmonary infections justify use of this drug.
• Cryptococcus: Limited trials in septicemias and urinary tract infections, but good responses reported.

Uses: For the treatment of serious infections due to susceptible strains of Candida (septicemia, endocarditis, urinary system infections, pulmonary infections) and/or Cryptococcus (meningitis, pulmonary infections, septicemia, urinary tract infections)

Infectious Diseases Society of America (IDSA) Recommendations: 100 mg/kg/day orally in 4 divided doses

Comments:

• In conjunction with amphotericin B (or fluconazole)
• Current guidelines should be consulted for additional information.

Usual Adult Dose for Fungal Endocarditis

50 to 150 mg/kg/day orally in divided doses every 6 hours

Comments:

• This drug should be used in conjunction with amphotericin B for the treatment of systemic candidiasis and cryptococcosis (due to emerging resistance to this drug).
• Candida: Limited studies in pulmonary infections justify use of this drug.
• Cryptococcus: Limited trials in septicemias and urinary tract infections, but good responses reported.

Uses: For the treatment of serious infections due to susceptible strains of Candida (septicemia, endocarditis, urinary system infections, pulmonary infections) and/or Cryptococcus (meningitis, pulmonary infections, septicemia, urinary tract infections)

Infectious Diseases Society of America (IDSA) Recommendations: 100 mg/kg/day orally in 4 divided doses

Comments:

• In conjunction with amphotericin B (or fluconazole)
• Current guidelines should be consulted for additional information.

Usual Adult Dose for Systemic Fungal Infection

50 to 150 mg/kg/day orally in divided doses every 6 hours

Comments:

• This drug should be used in conjunction with amphotericin B for the treatment of systemic candidiasis and cryptococcosis (due to emerging resistance to this drug).
• Candida: Limited studies in pulmonary infections justify use of this drug.
• Cryptococcus: Limited trials in septicemias and urinary tract infections, but good responses reported.

Uses: For the treatment of serious infections due to susceptible strains of Candida (septicemia, endocarditis, urinary system infections, pulmonary infections) and/or Cryptococcus (meningitis, pulmonary infections, septicemia, urinary tract infections)

Infectious Diseases Society of America (IDSA) Recommendations: 100 mg/kg/day orally in 4 divided doses

Comments:

• In conjunction with amphotericin B (or fluconazole)
• Current guidelines should be consulted for additional information.

Usual Pediatric Dose for Systemic Fungal Infection

American Academy of Pediatrics Recommendations: 100 mg/kg/day orally in divided doses every 6 hours

Comments:

• Dose should be adjusted for renal dysfunction and neonatal age; 2-hour post-peak levels should be followed closely (therapeutic range: 25 to 100 mcg/mL).
• This drug should be used in conjunction with amphotericin B for the treatment of cryptococcosis (due to emerging resistance to this drug).
• Current guidelines should be consulted for additional information.

Renal Dose Adjustments

Dose adjustments may be required; however, no specific guidelines have been suggested. Extreme caution recommended.

Comments:

• If BUN or serum creatinine is elevated (or there are other signs of renal dysfunction), the lower amount should be used for the initial dose.

Some Experts Recommend:

• CrCl at least 40 mL/min: 25 mg/kg orally every 6 hours
• CrCl 20 to 40 mL/min: 25 mg/kg orally every 12 hours
• CrCl 10 to 20 mL/min: 25 mg/kg orally every 24 hours
• CrCl less than 10 mL/min: 25 mg/kg orally every 48 hours

Comments:

• If available, therapeutic drug monitoring is recommended for all patients to guide optimal dosing; target peak level (2 hours post-dose): 30 to 80 mcg/mL

Liver Dose Adjustments

Data not available

Precautions

US BOXED WARNING:

• RENAL IMPAIRMENT/MONITORING: This drug should be used with extreme caution in patients with renal dysfunction. Close monitoring of renal, hematologic, and hepatic status of all patients is essential. Instructions should be reviewed thoroughly before use of this drug.

CONTRAINDICATIONS:
Known hypersensitivity to the drug

Safety and efficacy have not been systematically studied in patients younger than 18 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Comments:

• Hemodialysis rapidly reduces serum drug levels in anuric patients.

Some Experts Recommend:

• Hemodialysis: 25 to 50 mg/kg orally every 48 to 72 hours, after dialysis session

Comments:

• If available, therapeutic drug monitoring is recommended for all patients to guide optimal dosing; target peak level (2 hours post-dose): 30 to 80 mcg/mL

Other Comments

Administration advice:

• May minimize or avoid nausea/vomiting if the capsules are administered a few at a time over 15 minutes
• Use in conjunction with amphotericin B for the treatment of systemic candidiasis and cryptococcosis (due to emerging resistance to this drug); according to some experts, may use with oral fluconazole in patients who cannot receive amphotericin B.

General:

• Duration of therapy depends on the nature and severity of the infection.
• A small number of neonates were treated with 25 to 200 mg/kg/day (with and without amphotericin B) for systemic candidiasis; no unexpected side effects were reported. The manufacturer product information should be consulted for additional information.

Monitoring:

• General: Serum drug levels (during therapy)
• Hematologic: Hematologic status including leukocyte and thrombocyte count (before and often during therapy); hematopoietic system (often during therapy)
• Hepatic: Liver function including alkaline phosphatase, ALT, and AST (often during therapy)
• Metabolic: Electrolytes (before and during therapy)
• Renal: Renal function (before and during therapy)

See also:

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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