Flucytosine

Flucytosine: Uses, Dosage and Side Effects

Overview

• Fungal cells convert flucytosine (5-FC) into 5-fluorouracil (5-FU), which inhibits DNA and RNA synthesis in the cell.
• Mammalian cells are spared.
• Penetrates well into cerebrospinal fluid.

Uses of Flucytosine

• Treatment of cryptococcosis (often in conjunction with amphotericin B or itraconazole) particularly if involving meninges; systemic and urinary yeast infections (e.g. candidiasis).

Dose of Flucytosine in Dogs and Cats

Dogs:

• Fungal infections: 25–35 mg/kg i.v. q8h or 50–65 mg/kg p.o. q8h.

Cats:

• Fungal infections: 25–50 mg/kg i.v. q6h or 50–65 mg/kg p.o. q8h.

Side Effects of Flucytosine in Dogs and Cats

• Drug eruptions, including toxic epidermal necrolysis.
• Vomiting and diarrhoea may develop as well as myelosuppression, renal and hepatic toxicity; alleviated by dosing over 15 minutes.
• Flucytosine may be teratogenic.

Contraindications of Flucytosine in Dogs and Cats

• No information is available.

Some Notes:

• Synergy with amphotericin B has been demonstrated, although there is an increased risk of nephrotoxicity.