Antifungal Drugs Flashcards
Amphotericin B
Action: Binds ergosterol and forms membrane pores; polyene.
Uses: Serious, systemic mycoses; Cryptococcus (amphotericin B with/without flucytosine for cryptococcal meningitis); Blastomyces; Coccidioides; Histoplasma, Candida; Mucor; intrathecally for fungal meningitis.
Toxicity: “Amphoterrible”; fever/chills; hypotension; nephrotoxicity; arrhythmias; anemia; IV phlebitis.
Other drugs in class: Nystatin (only topical; oral thrush; diaper rash; vaginal candidiasis).
Caspofungin
Action: Inhibits cell wall synthesis by inhibiting synthesis of β-glucan; Echinocandin.
Uses: Invasive aspergillosis; Candida.
Toxicity: GI upset; flushing (by histamine release).
Fluconazole
Action: Inhibits ergosterol synthesis by inhibiting the cytochrome P-450 enzyme that converts lanosterol to ergosterol; azole.
Uses: Local and less serious systemic mycoses; fluconazole for chronic suppression of cryptococcal meningitis in AIDS patients and candidal infections of all types; itraconazole for Blastomyces, Coccidioides, Histoplasma; clotrimazole and miconazole for topical fungal infections.
Toxicity: Testosterone synthesis inhibition; liver dysfunction (via P-450 inhibition).
Other drugs in class: Ketoconazole; clotrimazole; miconazole; itraconazole; voriconazole.
Flucytosine
Action: Inhibits DNA and RNA biosynthesis by conversion to 5-fluorouracil by cytosine deaminase.
Uses: Systemic fungal infections (esp. meningitis caused by Cryptococcus) in combination with amphotericin B.
Toxicity: Bone marrow suppression.
Griseofulvin
Action: Interferes with microtubule function = disrupts mitosis; deposits in keratin-containing tissues (e.g., nails).
Uses: Oral treatment of superficial infections.
Toxicity: Teratogenic; carcinogenic; confusion; headaches, P-450 induction; increased warfarin metabolism.
Terbinafine
Action: Inhibits ergosterol synthesis by inhibiting squalene epoxidase.
Uses: Dermatophytoses (especially onychomycosis).
Toxicity: GI upset; headaches; hepatotoxicity; taste disturbance.
