Flucytosine (5-FC)

C difficile risk
Oral Bioavailability
Good (70 to 90%)


<1200g≥1200gAge 0 to 28 days: 25 - 37.5 mg/kg/dose Q12H
Age >28 days: 25 - 37.5 mg/kg/dose Q6H - Q8H25 - 37.5 mg/kg/dose Q6H - Q8H

Infuse over 30 minutesUsed in combination with amphotericin B for the treatment of invasive fungal infections and meningitis


IV10 mg/mL

Supplied by Pharmacy

Room Temperature

Dosage adjustment required in renal impairment

General Information


  • Enterocolitis

  • Nausea/vomiting

  • Diarrhea

  • Hepatotoxicity

  • Bone marrow toxicity when serum flycytosine level is greater than 100 mg/L

Tablet: 500 mg
Suspension (BCCH): 100 mg/mL

Injectable: 10 mg/mL in isotonic sodium chloride

  • Do not use as a single antifungal agent. Resistance develops quickly when used as monotherapy.

  • Well absorbed after oral administration and distributes widely, with good penetration into CSF, vitreous and peritoneal fluids

Data from adult studies unless otherwise noted

Oral bioavailability: 78 to 89% (decreased in neonates)

Plasma Protein Binding: 3 to 4%

Elimination: Eliminated primarily as unchanged drug by the kidneys by glomerular filtration. Increase dosing interval in neonates with impaired renal function and monitor trough serum flucytosine levels closely