antibioticsbooks

Antifungal
Antimetabolites
28
Agent: flucytosine (5-FC)
Flucytosine has a mechanism of action that is distinct
from that of other antifungals in that it is an
antimetabolite that interferes with DNA synthesis.
Flucytosine was originally investigated as an
oncology drug, but it was found to be significantly
more active against fungi than against human
cancer cells. The primary role of flucytosine is in
combination therapy with amphotericin B formulations
for cryptococcal disease. Because of its toxicity
and relative lack of efficacy, it is rarely used for
other infections.
Mechanism of Action
Flucytosine is deaminated inside fungal cells to
5-fluorouracil, which is further converted into
metabolites that interfere with both protein and
DNA synthesis.
Spectrum
Good: in combination with amphotericin B: Cryptococcus
neoformans, most species of Candida
Moderate: monotherapy: Cryptococcus neoformans,
most species of Candida
Poor: molds, Candida krusei