Onecan 400 Tablet contains Fluconazole 400 mg, an antifungal agent belonging to the triazole class. It is primarily indicated for the treatment of various fungal infections caused by susceptible strains of Candida species, Cryptococcus neoformans, and other fungi. Fluconazole works by inhibiting the fungal cytochrome P450 enzyme 14α-demethylase, which is essential for converting lanosterol to ergosterol, a critical component of the fungal cell membrane. This disruption leads to increased membrane permeability and ultimately fungal cell death. Onecan 400 is commonly prescribed for oropharyngeal, esophageal, and systemic candidiasis, cryptococcal meningitis, and prophylaxis against fungal infections in immunocompromised patients, including those undergoing chemotherapy or organ transplantation. The tablet is administered orally, with dosage and duration tailored based on the type and severity of infection, as well as patient-specific factors such as renal function. Fluconazole is generally well-tolerated; however, potential adverse effects include headache, nausea, abdominal pain, and, rarely, hepatotoxicity or QT prolongation. Caution is advised when co-administered with drugs metabolized by cytochrome P450 enzymes due to possible interactions. Monitoring liver function and clinical response is recommended during prolonged therapy. Onecan 400 Tablet should be used under medical supervision to ensure safe and effective treatment of fungal infections.