5fluorotsütsiin

5-fluorotsütsiin, also known as flucytosine or 5-FC, is a synthetic fluorinated pyrimidine analog of cytosine. It is primarily used as an antifungal medication. Its mechanism of action involves its conversion within fungal cells to 5-fluorouracil (5-FU), a potent antimetabolite. This conversion is facilitated by the fungal enzyme cytosine deaminase, which is not significantly present in mammalian cells, contributing to the drug's selective toxicity against fungi. Once converted to 5-FU, it interferes with fungal DNA and RNA synthesis, ultimately inhibiting fungal growth and replication.

Flucytosine is typically administered orally, although intravenous formulations are also available. It is often used in combination with other antifungal agents, such as amphotericin B, to treat serious systemic fungal infections, particularly cryptococcosis and candidiasis. This combination therapy can enhance efficacy and reduce the development of resistance. The absorption of oral flucytosine is generally good.

Common side effects associated with flucytosine therapy include gastrointestinal disturbances such as nausea, vomiting, and diarrhea. Hematological abnormalities, including bone marrow suppression leading to leukopenia, thrombocytopenia, and anemia, are also a concern and require regular monitoring of blood counts. Liver function abnormalities can also occur. Due to potential toxicity, flucytosine therapy is usually reserved for severe infections and requires careful patient monitoring. It is not typically used as a monotherapy for most fungal infections due to the rapid development of resistance.