Lecture 16 - Antifungals & Antivirals Flashcards
Which portion of the cell membrane of fungi is resistant to antibiotics?
Ergosterol
What is amphotericin B?
Polyene macrolide
What produces amphotericin B?
Streptomyces nodosus
What is the use of amphotericin B?
- Life threatening disease; effective against wide range of fungi
- Used for candida, blastomyces, aspergillus, and protozoa
What does amphotericin B bind to?
Ergosterol
What is flucytosine?
Synthetic pyrimidine antimetabolite
What is flucytosine converted to?
5’ - fluorodeoxyuridine monophosphate (5-FdUMP)
What is the function of flucytosine?
Blocks thymidylic acid, which is needed for DNA
Flucytosine has synergy w/ ____
Amphotericin B
What is the spectrum of flucytosine?
Limited (candida and some molds)
How can flucytosine resistance develop?
Target enzyme can be down-regulated, leading to resistance
What is the toxic metabolite of flucytosine?
Fluorouracil
What is posaconazole?
Synthetic triazole for systemic fungi infection
What is the function of posaconazole?
- Inhibits C-14 alpha-demethylase (CYP P450 enzyme)
- Blocks demethylation of lanosterol to ergosterol
- Disrupts membrane structure/function
Can posaconazole be given orally?
Yes, needs gastric acid
What is the spectrum of posaconazole?
Species of candida and aspergillus
Posaconazole resistance is becoming a problem in ____ px
HIV
What is an inducer of posaconazole?
Rifampin
What is caspofungin?
New group of fungicide
What is the function of caspofungin?
- Inhibits beta-(1,3)-D-glycan
- Causes cell wall disruption and death
What is the spectrum of caspofungin?
Aspergillus and candida
What are some drugs used for subcutaneous and systemic mycotic infections?
- Amphotericin B
- Flucytosine
- Posaconazole
- Caspofungin
Which drug is used for cutaneous mycotic infections?
Terbinafine
What is the function of terbinafine?
Inhibits squalene epoxidase and blocks ergosterol
How long is terbinafine therapy?
3 months
How is terbinafine administered?
Oral
What is the problem w/ antiprotozoal drugs for eukaryotes?
Metabolism close to humans, to toxicity issues arise esp. against metabolically active cells
Can antiprozoal drugs be used in pregnant patients?
Nope
What does entamoeba histolytica cause?
- Fulminating diarrhea
- Liver abscess