Adult

Flucytosine

General Information

Unlicensed Restricted formulary antimicrobial: For details see OUH netFormulary

IV flucytosine has been discontinued globally. Unlicensed oral flucytosine remains available - for further information about supply discuss with pharmacy.

For all information regarding contra-indications, interactions, contraception, pregnancy and breastfeeding and additional information, see BNF and Summary of Product Characteristics (SPC).

Dosage

Standard Dose - 50 mg/kg po qds 

Cryptococcal meningitis – 25mg/kg po qds in combination with amphotericin B liposomal 

Obesity

Use ideal body weight to calculate dose. Carry out therapeutic drug monitoring.

Renal and hepatic impairment

Renal impairment

For dosing information see table below.

In patients with renal impairment monitor U&Es, LFTs and FBC regularly. Also carry out therapeutic drug monitoring.

eGFR

(ml/min/1.73m2)

Where usual dose would be

25mg/kg po qds

Where usual dose would be

50mg/kg po qds
Over 40 No adjustment No adjustment
20-40 25mg/kg bd 50mg/kg bd
10-20 25mg/kg od 50mg/kg od
Less than 10 25mg/kg 48 hourly

Discuss with Pharmacy

Dosing usually 50mg/kg stat then 0.5-1g daily

Dosing for patients with HD/HDF/High Flux or PD should be discussed with pharmacy or Micro/ID

 

Hepatic impairment

No dose adjustment. In patients with hepatic impairment monitor LFTs closely and carry out therapeutic drug monitoring.

 

Therapeutic Drug Monitoring

Therapeutic Drug Monitoring is required. See Therapeutic Drug Monitoring (TDM) for Antifungal Agents

MHRA Drug Safety Updates

MHRA Drug Safety Update (October 2020) Flucytosine (Ancotil): new contraindication in patients with DPD deficiency  

  • Do not delay therapy with flucytosine for pre-treatment testing of DPD deficiency; however, consider determination of DPD activity if drug toxicity is confirmed or suspected. In cases of drug toxicity, consider stopping treatment with flucytosine.

References

Editorial Information

Next review date: 01 May 2028