Flucytosine

5-Fluorocytosine

Flucytosine is a prominent antifungal agent utilized in the management of severe fungal infections, particularly those induced by Candida and Cryptococcus species.

Mechanism of Action

5-Fluorocytosine-3D-balls

Flucytosine, scientifically denoted as (floo sye' toe zeen), belongs to the category of fluorinated pyrimidine analogues. It operates with a powerful fungicidal mechanism. The drug is absorbed by the fungal cells and subsequently converted into fluorouracil. This compound inhibits pyrimidine metabolism and might even transform into metabolites that curtail DNA synthesis. Notably, human cells lack the requisite enzymes to metamorphose flucytosine into these detrimental metabolites, lending its specificity. This unique mechanism equips Flucytosine with activity against multiple Candidal and Cryptococcal species.

FDA Approval Information

The FDA granted approval for Flucytosine's medical use in the United States in 1971. However, its dominance in the antifungal spectrum waned over time as newer, more efficacious, and better-tolerated antifungal agents like amphotericin and the azoles entered the market.

Dosage and Administration

Flucytosine is commercially available in tablet forms, with concentrations of 250 mg and 500 mg. These are accessible in generic iterations and also under the commercial label 'Ancobon'. Medical practitioners typically recommend a dosage ranging between 50 to 150 mg/kg per day. This is divided and administered at regular intervals, typically every six hours. For enhanced efficacy, it's frequently co-administered with other antifungal drugs, with amphotericin B being the most common partner.

Side Effects

Patients administered with Flucytosine might experience a range of side effects. While some are common and relatively mild, such as nausea, vomiting, and headache, others are rare yet severe. Critical side effects encompass bone marrow suppression, potential renal failure, cardiac arrest, and the perilous skin reaction known as toxic epidermal necrolysis.

Liver Safety

While Flucytosine therapy is generally safe, there have been instances of transient elevations in serum aminotransferase. This drug has also been identified, albeit rarely, as a potential causative agent for acute drug-induced liver injury of clinical significance.

See Also

• Antifungal Agents
• Fluorinated pyrimidine analogues
• Serum aminotransferase
• FDA

• Dailymed label info on Flucytosine
• FDA Flucytosine