Lecture 16 - Antifungals & Antivirals Flashcards by Anna Van Dekerkhove

Which portion of the cell membrane of fungi is resistant to antibiotics?

Ergosterol

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What is amphotericin B?

Polyene macrolide

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What produces amphotericin B?

Streptomyces nodosus

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What is the use of amphotericin B?

Life threatening disease; effective against wide range of fungi
Used for candida, blastomyces, aspergillus, and protozoa

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What does amphotericin B bind to?

Ergosterol

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What is flucytosine?

Synthetic pyrimidine antimetabolite

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What is flucytosine converted to?

5’ - fluorodeoxyuridine monophosphate (5-FdUMP)

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What is the function of flucytosine?

Blocks thymidylic acid, which is needed for DNA

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Flucytosine has synergy w/ ____

Amphotericin B

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What is the spectrum of flucytosine?

Limited (candida and some molds)

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How can flucytosine resistance develop?

Target enzyme can be down-regulated, leading to resistance

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What is the toxic metabolite of flucytosine?

Fluorouracil

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What is posaconazole?

Synthetic triazole for systemic fungi infection

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What is the function of posaconazole?

Inhibits C-14 alpha-demethylase (CYP P450 enzyme)
Blocks demethylation of lanosterol to ergosterol
Disrupts membrane structure/function

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Can posaconazole be given orally?

Yes, needs gastric acid

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What is the spectrum of posaconazole?

Species of candida and aspergillus

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Posaconazole resistance is becoming a problem in ____ px

HIV

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What is an inducer of posaconazole?

Rifampin

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What is caspofungin?

New group of fungicide

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What is the function of caspofungin?

Inhibits beta-(1,3)-D-glycan

- Causes cell wall disruption and death

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What is the spectrum of caspofungin?

Aspergillus and candida

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What are some drugs used for subcutaneous and systemic mycotic infections?

Amphotericin B
Flucytosine
Posaconazole
Caspofungin

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Which drug is used for cutaneous mycotic infections?

Terbinafine

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What is the function of terbinafine?

Inhibits squalene epoxidase and blocks ergosterol

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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

What is the function of metronidazole?

Kills E. histolytica trophozoites

When are luminal amebicides used and what is an example?

- After systemic treatment | - Iodoquinol

What is iodoquinol used for?

Cyst and trophozoite forms

When are systemic amebicides used and what is an example?

- Useful for liver abscess or intestinal wall infection | - Chloroquine

What is the chemotherapy for malaria?

Plasmodium falciparum and plasmodium vivax

What are symptoms of malaria cytotoxicity?

- High fever - Orthostatic hypotension - Erythrocytosis - Capillary obstruction - Anemia - Raised intracranial pressure

How long does it take malaria to infect the liver?

30 minutes

What is primaquine?

Tissue schizonticide

What is primaquine effective against?

- Primary/secondary exoerythrocytic forms (mainly in liver) | - Kills as gametocytic forms, does not affect erythrocytic form

How is primaquine administered?

Oral

What is chloroquine effective against w/ respect to malaria?

Systemic amebiosis

What is trypanosomiasis?

Disease that lives and grows in blood cells, and then enters CNS and causes inflammation

When is malrsoprol used?

Late stage w/ CNS signs of trypanosomiasis

What is the function of melarsoprol?

Reacts w/ sulfhydryl residues on enzymes

Nifurtimox is ___ specific

T. cruzi (generates ROS which T. cruzi doesn't have catalase against)

When is suramin used?

Early tx of trypanosomiasis

What are some other protozoan-related diseases?

- Leishmaniasis (skin sores) - Toxoplasmosis - Giardiasis

Describe the chemotherapy for leishmaniasis

3 types - cutaneous, mucocutaneous, and visceral

What drugs are used for leishmaniasis?

Sodium stibogluconate (inhibitis glycolysis) and amphotericin B (unknown mechanism)

What are some characteristics of viruses?

- Obligate intracellular parasites - No cell wall or plasmamembrane - No metabolism (so tough to target)

What is the function of viral proteins?

- Induce lysis or apoptosis | - Trigger host immune response

What is the life cycle HSV?

- Lytic cycle in epithelial cells - Retrogradely transported to cell body - Latent, but stress-related reactivation - Anterograde transport

What is the function of acyclovir?

- Acyclo-GTP inhibitor of viral DNA polymerase - Viral DNA chain termination - Tx for genital herpes, shingles, cold sores, and chicken pox - Oral or IV

What are some HSV drugs?

- Acyclovir - Famciclovir - Penciclovir - Docosanol

What are some drugs to treat CMV?

- Ganciclovir - Valganciclovir - Foscarnet

What does HIV do?

- Invades helper T cells (CD4) and macrophages and dendritic cells - Targets CD4 receptors and chemokine co-receptors - Causes loss of CD4 cells and cell-mediated immunity

What are the tx options for HIV?

- Highly active anti-retroviral therapy | - No cure

What are the drug classes used for HIV tx?

- Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) - Non-nucleoside/nucleotide reverse transcriptase inhibitors (NNRTIs) - HIV protease inhibitors - HIV integrase strand transfer inhibitors

Which drugs are NRTIs?

- Zidovudine - Abacavir - Lamivudine - Emtricitabine - Tenofovir

Which drugs are NNRTIs?

- Efavirenz | - Nevirapine

What is an important drug interaction w/ HIV protease inhibitors?

Linked to inhibition of CYP isozymes

Which drugs are HIV integrase strand transfer inhibitors?

- Dolutegravir - Elvitegravir - Raltegravir

When are viral fusion inhibitors used?

For multidrug resistant HIV

Which drug is a viral fusion inhibitor?

Enfuvirtide

Which drug is a co-receptor inhibitor?

Maraviroc

Which flu virus is more severe?

Flu A

What is the function of neuraminidase inhibitors?

- Cleave glycosidic linkages on neuraminic (sailic) acid | - Permits release of viral particle from host cell

Which drugs are neuraminidase inhibitors?

Zanamivir and oseltamivir

Which drugs are inhibitors of viral uncoating?

Amantadine and rimantadine

What is the function of inhibitors of viral uncoating?

- Block M2 channel - Prevent acidification of viral particle - Stop release of viral genome and uncoating - Effective early therapy for influenza A

Which hepatitis virus is most common?

Hepatitis B

When is interferon tx used?

Only for chronic infections

Which drugs are anti-HBV drugs?

- Lamivudine - Tenofovir - Ribavirin

Which drugs are protease inhibitors?

Boceprevir, sofosbuvir, and telaprevir

HIV and HBV use which enzyme?

Reverse transcriptase

Lecture 16 - Antifungals & Antivirals Flashcards

(74 cards)