Lecture 16 - Antifungals & Antivirals Flashcards

1
Q

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

A

Ergosterol

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2
Q

What is amphotericin B?

A

Polyene macrolide

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3
Q

What produces amphotericin B?

A

Streptomyces nodosus

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4
Q

What is the use of amphotericin B?

A
  • Life threatening disease; effective against wide range of fungi
  • Used for candida, blastomyces, aspergillus, and protozoa
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5
Q

What does amphotericin B bind to?

A

Ergosterol

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6
Q

What is flucytosine?

A

Synthetic pyrimidine antimetabolite

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7
Q

What is flucytosine converted to?

A

5’ - fluorodeoxyuridine monophosphate (5-FdUMP)

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8
Q

What is the function of flucytosine?

A

Blocks thymidylic acid, which is needed for DNA

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9
Q

Flucytosine has synergy w/ ____

A

Amphotericin B

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10
Q

What is the spectrum of flucytosine?

A

Limited (candida and some molds)

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11
Q

How can flucytosine resistance develop?

A

Target enzyme can be down-regulated, leading to resistance

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12
Q

What is the toxic metabolite of flucytosine?

A

Fluorouracil

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13
Q

What is posaconazole?

A

Synthetic triazole for systemic fungi infection

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14
Q

What is the function of posaconazole?

A
  • Inhibits C-14 alpha-demethylase (CYP P450 enzyme)
  • Blocks demethylation of lanosterol to ergosterol
  • Disrupts membrane structure/function
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15
Q

Can posaconazole be given orally?

A

Yes, needs gastric acid

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16
Q

What is the spectrum of posaconazole?

A

Species of candida and aspergillus

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17
Q

Posaconazole resistance is becoming a problem in ____ px

A

HIV

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18
Q

What is an inducer of posaconazole?

A

Rifampin

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19
Q

What is caspofungin?

A

New group of fungicide

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20
Q

What is the function of caspofungin?

A
  • Inhibits beta-(1,3)-D-glycan

- Causes cell wall disruption and death

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21
Q

What is the spectrum of caspofungin?

A

Aspergillus and candida

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22
Q

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

A
  • Amphotericin B
  • Flucytosine
  • Posaconazole
  • Caspofungin
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23
Q

Which drug is used for cutaneous mycotic infections?

A

Terbinafine

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24
Q

What is the function of terbinafine?

A

Inhibits squalene epoxidase and blocks ergosterol

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25
Q

How long is terbinafine therapy?

A

3 months

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26
Q

How is terbinafine administered?

A

Oral

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27
Q

What is the problem w/ antiprotozoal drugs for eukaryotes?

A

Metabolism close to humans, to toxicity issues arise esp. against metabolically active cells

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28
Q

Can antiprozoal drugs be used in pregnant patients?

A

Nope

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29
Q

What does entamoeba histolytica cause?

A
  • Fulminating diarrhea

- Liver abscess

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30
Q

What is the function of metronidazole?

A

Kills E. histolytica trophozoites

31
Q

When are luminal amebicides used and what is an example?

A
  • After systemic treatment

- Iodoquinol

32
Q

What is iodoquinol used for?

A

Cyst and trophozoite forms

33
Q

When are systemic amebicides used and what is an example?

A
  • Useful for liver abscess or intestinal wall infection

- Chloroquine

34
Q

What is the chemotherapy for malaria?

A

Plasmodium falciparum and plasmodium vivax

35
Q

What are symptoms of malaria cytotoxicity?

A
  • High fever
  • Orthostatic hypotension
  • Erythrocytosis
  • Capillary obstruction
  • Anemia
  • Raised intracranial pressure
36
Q

How long does it take malaria to infect the liver?

A

30 minutes

37
Q

What is primaquine?

A

Tissue schizonticide

38
Q

What is primaquine effective against?

A
  • Primary/secondary exoerythrocytic forms (mainly in liver)

- Kills as gametocytic forms, does not affect erythrocytic form

39
Q

How is primaquine administered?

A

Oral

40
Q

What is chloroquine effective against w/ respect to malaria?

A

Systemic amebiosis

41
Q

What is trypanosomiasis?

A

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

42
Q

When is malrsoprol used?

A

Late stage w/ CNS signs of trypanosomiasis

43
Q

What is the function of melarsoprol?

A

Reacts w/ sulfhydryl residues on enzymes

44
Q

Nifurtimox is ___ specific

A

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

45
Q

When is suramin used?

A

Early tx of trypanosomiasis

46
Q

What are some other protozoan-related diseases?

A
  • Leishmaniasis (skin sores)
  • Toxoplasmosis
  • Giardiasis
47
Q

Describe the chemotherapy for leishmaniasis

A

3 types - cutaneous, mucocutaneous, and visceral

48
Q

What drugs are used for leishmaniasis?

A

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

49
Q

What are some characteristics of viruses?

A
  • Obligate intracellular parasites
  • No cell wall or plasmamembrane
  • No metabolism (so tough to target)
50
Q

What is the function of viral proteins?

A
  • Induce lysis or apoptosis

- Trigger host immune response

51
Q

What is the life cycle HSV?

A
  • Lytic cycle in epithelial cells
  • Retrogradely transported to cell body
  • Latent, but stress-related reactivation
  • Anterograde transport
52
Q

What is the function of acyclovir?

A
  • Acyclo-GTP inhibitor of viral DNA polymerase
  • Viral DNA chain termination
  • Tx for genital herpes, shingles, cold sores, and chicken pox
  • Oral or IV
53
Q

What are some HSV drugs?

A
  • Acyclovir
  • Famciclovir
  • Penciclovir
  • Docosanol
54
Q

What are some drugs to treat CMV?

A
  • Ganciclovir
  • Valganciclovir
  • Foscarnet
55
Q

What does HIV do?

A
  • 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
56
Q

What are the tx options for HIV?

A
  • Highly active anti-retroviral therapy

- No cure

57
Q

What are the drug classes used for HIV tx?

A
  • Nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs)
  • Non-nucleoside/nucleotide reverse transcriptase inhibitors (NNRTIs)
  • HIV protease inhibitors
  • HIV integrase strand transfer inhibitors
58
Q

Which drugs are NRTIs?

A
  • Zidovudine
  • Abacavir
  • Lamivudine
  • Emtricitabine
  • Tenofovir
59
Q

Which drugs are NNRTIs?

A
  • Efavirenz

- Nevirapine

60
Q

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

A

Linked to inhibition of CYP isozymes

61
Q

Which drugs are HIV integrase strand transfer inhibitors?

A
  • Dolutegravir
  • Elvitegravir
  • Raltegravir
62
Q

When are viral fusion inhibitors used?

A

For multidrug resistant HIV

63
Q

Which drug is a viral fusion inhibitor?

A

Enfuvirtide

64
Q

Which drug is a co-receptor inhibitor?

A

Maraviroc

65
Q

Which flu virus is more severe?

A

Flu A

66
Q

What is the function of neuraminidase inhibitors?

A
  • Cleave glycosidic linkages on neuraminic (sailic) acid

- Permits release of viral particle from host cell

67
Q

Which drugs are neuraminidase inhibitors?

A

Zanamivir and oseltamivir

68
Q

Which drugs are inhibitors of viral uncoating?

A

Amantadine and rimantadine

69
Q

What is the function of inhibitors of viral uncoating?

A
  • Block M2 channel
  • Prevent acidification of viral particle
  • Stop release of viral genome and uncoating
  • Effective early therapy for influenza A
70
Q

Which hepatitis virus is most common?

A

Hepatitis B

71
Q

When is interferon tx used?

A

Only for chronic infections

72
Q

Which drugs are anti-HBV drugs?

A
  • Lamivudine
  • Tenofovir
  • Ribavirin
73
Q

Which drugs are protease inhibitors?

A

Boceprevir, sofosbuvir, and telaprevir

74
Q

HIV and HBV use which enzyme?

A

Reverse transcriptase