ANTIFUNGAL DRUGS
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- What are the polyenes?
- Polyenes (Amphotericin and Nystatin) are characterized by a conjugated double bond system w a macrolide ring
- What makes the polyenes selctive?
- Amphotericin B and Nystatin have a higher affinity for ERGOSTEROL than for cholesterol and are therefore selective for fungal membranes
- Which polyene is more potent?
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AMphotericin B is 6X more potent than Nystatin and is soluble enough to be administered IV.
Nephrotoxicity - How do the AZOLES work?
- inhibition of 14-alfa-demethylase, a CYP450 involved in ergosterol synthesis.
- What are the 3 things you NEED to know about the various AZOLES?
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ITRACONAZOLE- oral tx of nail infection, DOC for dermatophytoses and onychomycosis
VORICONAZOLE- DOC invasive aspergillosis
FLUCONAZOLE- good CNS penetration, superior for tx of AIDS assoc Cryptococcal meningitis - What is he one allylamine we study?
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TERBINAFINE
by inhibiting fungal squalene epoxidase the effect is two fold:
1)inhibit membrane synthesis
2)toxic buildup of squalene - What is the ONLY approved drug for the topical tx of dermatophyte infections of hair and nails?
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Ciclopirox olamine!
a pyridone antifungal agent that inhibits the uptake of extracellular nutrients - Why is flucytosine used almost exclusively with Amphotericin B?
- bc clinical resistance occurs frequently
- What major pathogen is GRISEOFULVIN not effective against?
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Candida infections
insoluble cmpd effective in tx of fungal infections of skin, hair and mails caused by Epidermophyton, Microsporum, and Trichophyton. - What is important to know about Griseofulvin?
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it is virtually INSOLUBLE in H2O and is more readily absorbed if taken w a fatty meal
Absorption from gut is inhibited by barbituates