Anti-Fungal Drugs (Habal) Flashcards
What fungi cause superficial infections?
Dermatophytes
Malassezia furfur
What fungi cause subcutaneous infections?
Sporothrix schenckii
Basidiobolus ranierum
What fungi cause primary systemic infections?
Histoplasma capsulatum
Blastomyces dermatitidis
Coccidiodes immitis
Paracoccidiodes brasiliensis
What fungi cause primary opportunistic infections?
Candida albicans Cryptococcus neoformans Aspergillus fumigatus Mucor/Rhizopus Pneumocystis jirovecii
What are possible targets of anti-fungal drugs?
Cell wall Cell membrane Nucleus Vacuoles Cytoplasm Mitochondria
What is the fungal cell wall made up of?
Chitin, glucan, mannan
What is the fungal cell membrane made up of?
Phospholipids & sterols (ergosterol)
What are the 3 classes of antifungal drugs?
Cell wall (glucan) synthesis Cell membrane (ergosterol) synthesis DNA/RNA synthesis (pyrimidine analogues)
An optimal antifungal will have?
Wide spectrum of availability Favorable bioavailablity Adeqhate in vivo efficacy High therapeutic index Low cost
Anti-fungal antibiotics include what drugs?
Polyenes - Amphotericine B, Nystatin
Griseofluvn
Anti-fungal antimetabolites include?
Flucytosine
Anti-fungal azoles include?
Imidazoles - Ketoconazole, Miconazole
Triazoles - Itraconazole, Fluconazole
Anti-fungal allylamines include?
Terbinafine
What do allylamines such as Terbinafine interfere with?
Squalene epoxidase
What do azoles such as Ketoconazole, Fluconazole, Itraconazole, and Miconazole interfere with?
Cytochrome P450 14-alpha demethylase
What do polyenes such as Amphotericine B and Nystatin do?
Interact with ergosterol and form holes in cell membrane, affecting the integrity of its structure.
What resistance might you see against polyenes?
Low amount of ergosterol. If there’s nothing to interact with, then there can’t be an anti-fungal activity.
Are polyenes stable or unstable when taken orally?
Unstable
At what concentration are polyenes fungasidal?
High
What produces Amphotericin B?
Streptomyces nodosus
What broad spectrum anti-fungal drug is indicated for treatment of severe to life-threatening fungal infections?
Amphotericin B
How is Amphotericin B administered? Why?
IV only; very toxic, especially to the kidneys. Slow-rate IV infusion in a hospital setting is the best way to overcome/sidestep this toxicity.
What causes tubular nephrotoxicity due to administration of Amphotericin B?
Leakage of Na+, K+, Ca+
Which anti-fungal drug is the big gun?
Amphotericin B