Tozene Dosage/Direction for Use

Flucytosine is administered orally.
The usual dosage of Flucytosine is 50-150 mg/kg daily, administered in 4 equally divided doses at 6-hour intervals. Nausea and vomiting associated with oral Flucytosine may be reduced or avoided if each dose is administered by ingesting the capsules a few at a time over a 15-minute period.
To reduce the risk of toxicity when Flucytosine is used concomitantly with another antifungal, Flucytosine dosage should be carefully adjusted based on serum concentrations of the drug and patients receiving such therapy should be monitored closely for adverse effects. In addition, intrinsic resistance or emergence of resistance to Flucytosine may develop during therapy, it has been recommended that in vitro susceptibility tests be performed prior to and during Flucytosine therapy, whenever available.
Serum Flucytosine concentrations should be measured after 3-5 days of therapy and whenever there is evidence of toxicity or a change in renal function. Peak serum concentrations usually are measured using samples taken 2 hours after an oral dose.
Concomitant use of amphotericin B and Flucytosine for initial treatment of cryptococcosis may reduce the time required for sterilization of CSF in patients with CNS involvement.
Antifungal synergism between Flucytosine and polyene antibiotics, particularly amphotericin B has been reported in vitro. Flucytosine is usually administered in combination with amphotericin B due to lack of cross-resistance and reported synergistic activity of both drugs.
Use in patients with renal impairment: The following adjustments have been recommended (based on a usual dose of 25 mg/kg/dose every 6 hours): see Table.

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End-stage renal disease on intermittent hemodialysis: 25 to 50 mg/kg every 48-72 hours, administer dose after hemodialysis.
Use in patients with hepatic impairment: There are no dosage adjustments provided. Use with cautions.