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05 Deja Review-Micro Antifungal Drugs

Terms in this set (26)

What is the treatment for oral thrush?
Nystatin
Amphotericin B is associated with several toxicities. What is the most severe reaction?
Renal toxicity, including chronic azotemia, hypomagnesemia, hypokalemia, and renal tubular acidosis. Reversible toxicity occurs in 80% of patients treated with intravenous (IV) amphotericin B. Normochromic, normocytic anemia occurs often but usually does not require treatment.
What organisms is amphotericin B effective against?
Virtually every fungus. Some resistance has been reported among Candida species, but it remains the treatment of choice for virtually any life-threatening fungal infection.
What is the mechanism of action for amphotericin B?
Amphotericin B binds to sterols (eg, er- gosterol) in fungal membranes and creates pores into the membrane leading to cell death.
What is lipid-based amphotericin B?
Amphotericin B is encased in a liposomal vesicle or lipid-based vesicle. It is associated with less toxicity.
Fluconazole belongs to which family of anti-fungal drugs?
The triazole family. Other members are
itraconazole and voriconazole.
What is the mechanism of action for the triazoles?
Inhibition of the enzyme cytochrome P450 14α-demethylase, which converts lanosterol to ergosterol. It thus inhibits fungal steroid synthesis.
What are the major toxicities associated with fluconazole?
Although fluconazole is very well tolerated, associated side effects include gastrointestinal (GI) discomfort, rash, headache, liver toxicity (rarely), and alopecia (from long-term treatment).
Is fluconazole safe in pregnancy?
No. Fetal damage has been documented.
Do triazoles inhibit or induce the P450 system?
They inhibit the P450 enzymes. This can lead to interactions with warfarin, digitalis, cisapride, and so on.
What medication should not be administered with itraconazole?
Antacids or H2-inhibitors/proton pump inhibitors (PPIs). Itraconazole requires acidic pH for dissolution of capsules and should be given 2 hours before or after any antacids or H2-inhibitors/PPIs.
Ketoconazole belongs to which family of anti-fungal drugs?
The imidazole family. Other members are clotrimazole and miconazole.
What is the mechanism of action of imidazoles?
Inhibition of the enzyme cytochrome P450 14α-demethylase, which converts lanosterol to ergosterol. Same mechanism as triazoles
What type of infections are the imidazoles used for?
Superficial infections. Ketoconazole is the treatment of choice for tinea versicolor and mucocutaneous candidiasis. Imidazole creams are used for yeast infections and various tinea infections. All have activity against Candida infections.
What toxicities are associated with ketoconazole?
Liver toxicity, GI upset, thrombocytopenia, and photophobia. Gynecomastia due to inhibition of estrogen metabolism also occurs.
Is ketoconazole an inhibitor or inducer of the P450 system?
Ketoconazole is a strong inhibitor of P450 enzymes.
How does flucytosine work as an antifungal medication?
It is converted to 5-fluorouracil in fungal cells and works as an antimetabolite.
Why does flucytosine not kill human cells?
Human cells lack the cytosine deaminase enzyme that converts flucytosine to 5-fluorouracil.
What life-threatening toxicity is associated with flucytosine treatment?
Leukopenia and thrombocytopenia (especially in those who receive high-dose flucytosine). Non-life-threatening GI toxicity occurs more commonly.
What drugs should be used with caution along with flucytosine?
Any other medications that can cause bone marrow suppression (eg, ganciclovir, zidovudine, anticancer medications)
How does terbinafine work?
It inhibits squalene epoxidase, another enzyme required for ergosterol synthesis.
What infections is terbinafine used for?
Dermatophyte infections. It is used topically for tinea infections and can be given orally for some onychomycosis.
How does caspofungin work?
It inhibits the enzyme D-glucan synthase and disrupts the integrity of the fungal cell wall.
What infections is caspofungin used for?
Fungal infection in febrile neutropenic adult patients, invasive aspergillosis, and candidemia when not responsive to other treatment
How does griseofulvin work?
Binds to polymerized microtubules and inhibits mitosis
What infections is griseofulvin used for?
Tinea
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