Antifungal (pyrimidine analogue)
Flucytosine
Brand names: Ancotil
Adult dose
Dose: 50mg/kg every 6h IV (or PO equivalent); duration per indication. Reduce in renal impairment
Route: IV/PO
Frequency: q6h
Dose adjustments
Renal
Mandatory dose adjustment by CrCl — refer to BNF
Clinical pearls
- Combined with amphotericin B for cryptococcal meningitis induction
- Always combination therapy — monotherapy resistance
Contraindications
- Severe renal impairment without monitoring
Side effects
- Bone marrow suppression (dose-related)
- Hepatotoxicity
- GI upset
- Confusion
- Cardiotoxicity
Interactions
- Cytarabine (antagonism)
- Amphotericin (synergy but additive nephrotoxicity)
- Nephrotoxic drugs
Monitoring
- Plasma levels (target 25–50 mg/L peak; trough <25)
- FBC
- LFTs
- U&E
Reference: BNF; BHIVA opportunistic infection guidance; SmPC; https://bnf.nice.org.uk/drugs/flucytosine/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Pathways
- Infective Endocarditis · ESC 2023 Infective Endocarditis Guidelines; NICE NG41
- Eczema Herpeticum · BAD; NICE CKS
- Suspected Bacterial Meningitis (Adult) · NICE NG240 (2024); NICE NG143 (paeds)
- Clostridioides difficile Colitis · NICE NG199 (2021); IDSA/SHEA 2021
- Returning Traveller — Fever · NaTHNaC; PHE; ESCMID 2018
- Malaria — Diagnosis & Management · PHE 2016; WHO 2023