Anti-fungals Flashcards
There are two major classification of mycoses. What are they? What are some examples of each?
Systemic:
Opportunistic - Aspergillus, Candida, Phycomyces, Cyptococcus, Histoplasma
Geographically localized - Blastomyces, Histoplasma, Coccidioides, Sporothrix
Superficial:
Mucous membranes - Candida
Dermatophytic - Trichophyton, Microsporum, Epidermophyton
What are some potential antifungal targets?
- Membranes - Ergosterol
- Nucleic acids (limited)
- Cell wall (1 drug class)
What drugs are used for systemic fungal infections?
- Amphotericin B
- Flucytosine
- Fluconazole/Itraconazole/Voriconazole
- Caspofungin
What is the spectrum of action for Amphotericin B?
Effective for most serious systemic mycoses: especially those that are immediately life threatening.
It is the gold standard for anti-fungal effectiveness by which other drugs are judged.
Why should Amphotericin B only be used for proven or highly suspected systemic infections?
The side effects are particularly intense
What is the mechanism of action of Amphotericin B?
Binds to ergosterol in fungal membrane after inserting itself into membrane. This causes leaks in the fungal membrane.
- What is the most serious side effect of Amphotericin B?
- What are some other serious side effects?
- Permanent renal toxicity - total cumulative dose is major determinant.
- Hypotension, Hypokalemia, Tachypnea
90% show temporary nephrotoxicity
Reversible hypochromic, normocytic anemia
- What fungi are treated effectively with Flucytosine (5-FC)?
- Is it used alone or in combination therapy?
- **Candida, Cryptococcus*
- Used in conjunction with Amphotericin B
- **Candida, Cryptococcus*
What is the mechanism for Flucytosine?
Converted to 5-FU by fungal cytosine deaminase
Inhibits thymidylate synthetase and thus DNA synthesis and is also incorporated in RNA in place of uracil.
What are the major side effects of Flucytosine?
- Leukopenia, Thrombocytopenia
- Reversible elevated hepatic enzymes
- Extreme caution needed with patients who have renal insufficiency and bone marrow depression.
What are the three Triazole drugs used for serious fungal infections?
Fluconazole
Voriconazole
Itraconazole
What is the mechanism for imidAZOLES and triAZOLES?
Inhibits 14-alpha-sterol demethylase, a fungal P450 that converts lanosterol to ergosterol.
- What are the two fungal species that are treated well with Fluconazole?
- Which *Candida *species does Fluconazole not cover?
- Cryptococcus (meningitis), Candida.
- C. krusei
- What non-candida species does itraconazole cover?
- What is itraconazole’s relative candida coverage?
- Blastomyces, Histoplasma
- It has moderate coverage but does not penetrate CNS or urinary.
- What non-candida species does voriconazole cover?
- What is the relative candida coverage for voriconazole?
- Aspergillus
- Extensive coverage but does not treat urinary infection