What is the mechanism of action of flucytosine?

Flucytosine functions as an antifungal agent primarily by disrupting RNA and DNA synthesis within fungal cells. This drug is a pyrimidine analog that gets converted intracellularly into fluorouracil, which then inhibits the enzyme thymidylate synthase. This inhibition prevents the synthesis of thymidine, a crucial component necessary for DNA replication. Consequently, the interference with RNA and DNA synthesis affects fungal cell proliferation, leading to cell death.

The mechanism highlights flucytosine's specificity for fungal cells; since it relies on the conversion to fluorouracil by fungal enzymes, it exhibits selectivity over human cells. This targeted action distinguishes flucytosine while underscoring its role as a valuable antifungal treatment, especially when used in combination therapies to enhance efficacy and reduce resistance.