Anti Fungal Flashcards
What is the mechanism of Amphotericin B?
Binds ergosterol (unique to fungi) and forms membrane pores, allowing leakage of electrolytes.
Mnemonic: Amphotericin ‘tears’ holes in the fungal membrane by forming pores.
What are the clinical uses of Amphotericin B?
- Serious systemic mycoses:
- Cryptococcus (with or without flucytosine for cryptococcal meningitis)
- Blastomyces
- Coccidioides
- Histoplasma
- Candida
- Mucor
- Intrathecally for coccidioidal meningitis.
What are the adverse effects of Amphotericin B?
- Fever/chills (‘shake and bake’)
- Hypotension
- Nephrotoxicity
- Arrhythmias
- Anemia
- IV phlebitis (‘amphoterrible’)
- Supplement K+ and Mg2+ due to altered renal tubule permeability
- Hydration reduces nephrotoxicity
- Liposomal amphotericin reduces toxicity.
What is the mechanism of Nystatin?
Same as amphotericin B: Binds ergosterol and forms membrane pores, allowing leakage of electrolytes.
What are the clinical uses of Nystatin?
- Topical use only (too toxic for systemic use)
- ‘Swish and swallow’ for oral candidiasis (thrush)
- Topical for diaper rash or vaginal candidiasis.
What is the mechanism of Flucytosine?
Inhibits DNA and RNA biosynthesis by conversion to 5-fluorouracil (5-FU) by cytosine deaminase.
What are the clinical uses of Flucytosine?
- Systemic fungal infections (especially meningitis caused by Cryptococcus) in combination with amphotericin B.
What are the adverse effects of Flucytosine?
Myelosuppression.
Name some drugs classified as Azoles.
- Clotrimazole
- Fluconazole
- Isavuconazole
- Itraconazole
- Ketoconazole
- Miconazole
- Voriconazole.
What is the mechanism of Azoles?
Inhibit fungal sterol (ergosterol) synthesis by inhibiting the cytochrome P-450 enzyme that converts lanosterol to ergosterol.
What are the clinical uses of Azoles?
- Local and less serious systemic mycoses.
- Fluconazole: Chronic suppression of cryptococcal meningitis in people living with HIV and all types of candidal infections.
- Itraconazole: Blastomyces, Coccidioides, Histoplasma, Sporothrix schenckii.
- Clotrimazole and miconazole: Topical fungal infections.
- Voriconazole: Aspergillus and some Candida.
- Isavuconazole: Serious Aspergillus and Mucor infections.
What are the adverse effects of Azoles?
- Testosterone synthesis inhibition (gynecomastia, especially with ketoconazole)
- Liver dysfunction (inhibits cytochrome P-450)
- QT interval prolongation.
What is the mechanism of Terbinafine?
Inhibits the fungal enzyme squalene epoxidase.
What are the clinical uses of Terbinafine?
Dermatophytoses, especially onychomycosis (fungal infection of finger or toenails).
What are the adverse effects of Terbinafine?
GI upset, headaches, hepatotoxicity, taste disturbance.
Name some drugs classified as Echinocandins.
- Anidulafungin
- Caspofungin
- Micafungin.
What is the mechanism of Echinocandins?
Inhibit cell wall synthesis by inhibiting synthesis of β-glucan.
What are the clinical uses of Echinocandins?
Invasive aspergillosis, Candida infections.
What are the adverse effects of Echinocandins?
GI upset, flushing (caused by histamine release).
What is the mechanism of Griseofulvin?
Interferes with microtubule function, disrupting mitosis. Deposits in keratin-containing tissues (e.g., nails).
What are the clinical uses of Griseofulvin?
Oral treatment of superficial infections; inhibits growth of dermatophytes (e.g., tinea, ringworm).
What are the adverse effects of Griseofulvin?
- Teratogenic
- Carcinogenic
- Confusion
- Headaches
- Disulfiram-like reaction
- Induces cytochrome P-450 and warfarin metabolism.
Name some drugs used in Antiprotozoal Therapy.
- Pyrimethamine-sulfadiazine: Toxoplasmosis
- Suramin and melarsoprol: Trypanosoma brucei
- Nifurtimox: Trypanosoma cruzi (Chagas disease)
- Sodium stibogluconate: Leishmaniasis.
Name some drugs used in Anti-Mite/Louse Therapy.
- Permethrin: Blocks sodium channels causing paralysis of mite/louse
- Malathion: Acetylcholinesterase inhibitor
- Topical or oral ivermectin.
- Used to treat scabies (Sarcoptes scabiei) and lice (Pediculus and Pthirus).
What is the mechanism of Chloroquine?
Blocks detoxification of heme into hemozoin. Heme accumulates and is toxic to plasmodia.
What are the clinical uses of Chloroquine?
Treatment of plasmodial species other than P. falciparum (due to drug resistance from a membrane pump that reduces intracellular drug concentration).
What are the adverse effects of Chloroquine?
Retinopathy (cumulative dose-dependent), pruritus (especially in dark-skinned individuals).
