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Antivirals Flashcards

1
Q

Drug used in the treatment of Herpes Simplex Virus and Varicella Zoster Virus

A

Acyclovir

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2
Q

Mechanism of action for Acyclovir

A

It inhibits DNA synthesis in two ways. It competitively inhibits deoxyGTP which cause DNA template strand to bind to an inactive complex. It can also incorporate itself in the DNA strand and cause chain termination.

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3
Q

Toxicity of Acyclovir

A

Nausea, vomiting, and headache

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4
Q

Mechanism of resistance to Acyclovir

A

Alteration of thymidine kinase or DNA polymerase

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5
Q

Which drugs don’t require activation by thymidine kinase?

A

Cidofovir, foscarnet, and trifluridine

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6
Q

What is the only anti-HSV IV drug available?

A

Acyclovir

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7
Q

What is required to activate Acyclovir?

A

Three phosphorylation steps: first converted to monophosphate derivative and then to di- and tri- derivatives by host’s cellular enzymes

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8
Q

What 3 drugs are used to treat Cytomegalovirus?

A

Ganciclovir, Cidofovir, and Foscarnet

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9
Q

Mechanism of action of Ganciclovir

A

Competitively inhibits DNA polymerase and causes termination of the growing DNA strand

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10
Q

Mechanism of action of Cidofovir

A

Acts as a potent inhibitor and alternative substrate for viral DNA polymerase

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11
Q

Mechanism of action of Foscarnet

A

Inhibits viral DNA polymerase, RNA polymerase, and HIV reverse transcriptase without activation by phosphorylation. It blocks the pyrophosphate binding site of these enzymes and inhibits cleavage of pyrophosphate from deoxynucleotide triphosphates

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12
Q

Mechanism of resistance to Ganciclovir

A

Mutations in UL97 which activates the drug and UL54 which results in mutant DNA polymerase

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13
Q

Toxicity to Ganciclovir

A

Myelosuppression and Retinal detachment (in patients with CMV retinitis)

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14
Q

How many times greater is the activity of Ganciclovir against CMV compared to Acyclovir?

A

100 times greater

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15
Q

Toxicity to Cidofovir

A

Dose-dependent nephrotoxicity and decreased intraocular pressure

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16
Q

What type of analog is cidofovir?

A

Cytosine analog

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17
Q

What activates Cidofovir?

A

Human cell kinases

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18
Q

Toxicity of foscarnet

A

Nephrotoxicity, anemia, and CNS toxicity (headache, hallucinations, and seizures)

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19
Q

What type of analog is foscarnet?

A

It is an inorganic pyrophosphate analog

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20
Q

What viruses does foscarnet act against in-vivo?

A

HSV, VZV, CMV, and HIV-1

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21
Q

What two drugs are Nucleoside/Nucleotide Reverse Transcriptase Inhibitors?

A

Zidovudine and Tenofovir

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22
Q

What drug is a Non-Nucleoside/Nucleotide Reverse Transcriptase Inhibitor?

A

Nevirapine

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23
Q

Mechanism of action of Zidovudine and Tenofovir?

A

Binds to the DNA polymerase catalytic site on the reverse transcriptase enzyme which competitively inhibits DNA polymerase activity, and can be incorporated into the viral DNA chain causing termination

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24
Q

Mechanism of resistance to Zidovudine and Tenofovir?

A

viral mutations and there is cross-resistance between NRTIs

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25
Toxicity to Zidovudine and Tenofovir
Lactic acidemia and hepatomegaly
26
What is important about NRTIs in pregnancy?
Zidovudine is used to prevent vertical transmission from mother to child. If the mother is already in labor, Zidovudine can still be used.
27
What activates NRTIs?
human cell kinases in the cytoplasm
28
Mechanism of action for Non-Nucleoside/Nucleotide Reverse Transcriptase Inhibitors
Binds directly to sites on the reverse transcriptase enzyme resulting in allosteric inhibition of RNA and DNA-dependent DNA polymerase activities
29
Mechanism of resistance to Non-Nucleoside/Nucleotide Reverse Transcriptase Inhibitors
Viral mutations. No cross-resistance between NRTIs and NNRTIs or protease inhibitors
30
Toxicity to Non-Nucleoside/Nucleotide Reverse Transcriptase Inhibitors
GI intolerance and skin rash
31
Do NNRTIs need to be activated?
No
32
What is Nevirapine used for in pregnant women?
It is used to prevent transmission of HIV from mother to child via breastfeeding
33
What can occur within the first 6 weeks of treatment with Nevirapine?
Fulminant hepatitis
34
Which drugs are inhibitors of p450 CYP3A4?
Nevirapine, Ritonavir (protease inhibitors), Telaprevir, Boceprevir, Terbinafine, and Simeprevir
35
Which drugs are inducers of p450 CYP3A4?
Griseofulvin and NNRTIs
36
What drug class is ritonavir?
Protease inhibitor
37
Mechanism of action for ritonavir
Inhibits the protease enzyme which inhibits cleavage of the gag-pol enzyme which results in the production of immature, non-infectious viral particles
38
Mechanism of resistance to ritonavir
genotypic mutations (usually in monotherapy). Cross-resistance between protease inhibitors and appears to require a minimum of 4 substitutions in the gene
39
Toxicity to ritonavir
Lipodystrophy, increase in triglyceride and LDL levels, glucose intolerance, and insulin resistance
40
What types of HIV does ritonavir inhibit?
HIV-1 and HIV-2
41
What drug class is Enfuvirtide?
Fusion inhibitor
42
Mechanism of action for Enfuvirtide
blocks entry into the cell by binding to gp41 subunit on the viral envelope glycoprotein preventing conformational changes required for fusion of the virus
43
Mechanism of resistance to Enfuvirtide
It's still being studied. There is no cross-resistance between enfuvirtide and other antiretroviral drugs
44
Toxicity to Enfuvirtide
Injection site reactions and hypersensitivity reactions
45
Structure of Enfuvirtide
synthetic-amino-acid peptide
46
Route of administration for Enfuvirtide
Subcutaneous injection
47
What drug class is Maraviroc?
CCR5 Antagonist
48
Mechanism of action for Maraviroc
Binds to and blocks CCR5 on CD4 cells blocking HIV from invading CD4 cells. This only works in patients with CCR5-tropic disease so a patient must undergo testing/screening to determine tropism of their HIV infection before using Maraviroc
49
Toxicity to Maraviroc
Hepatotoxicity, cardiovascular events, increased risk of infections and malignancy
50
What two receptors does HIV use to invade CD4 cells?
CCR5 and CXCR4
51
What drug class is Raltegravir?
Integrase Strand Transfer Inhibitors
52
Mechanism of action for Raltegravir
Inhibits the integrase enzyme preventing viral DNA from integrating with cellular DNA
53
Mechanism of resistance to Raltegravir
mutations in the integrase enzyme
54
Toxicity to Raltegravir
Increased serum creatine kinase, myopathy, rhabdomyolysis
55
What is Raltegravir used for?
HIV-1 strains that are resistant to other antiretroviral drugs
56
What drug combination is used for Pre-Exposure Prophylaxis for HIV
Tenofovir and Emtricitabine
57
How can a patient become resistant to Tenofivir and Emtricitabine?
If they take the drugs and actually have the HIV infection
58
What is the treatment option for Post-Exposure Prophylaxis for HIV?
3 or more active antiretroviral drugs
59
What drugs are used in antiretroviral therapy?
Zidovudine, Tenofovir, Nevirapine, Ritonavir, Enfuviratine, Maraviroc, and Raltegravir
60
What drugs are used in Anti-hepatitis therapy?
Adefovir, Interferon Alfa, Ribavirin, Telaprevir + Boceprevir, Simeprevir, Sofosbuvir, and Sofosbuvir + Ledipasvir
61
Mechanism of action of Adefovir
Phosphorylated by cellular kinases to the active metabolite. Once activated, it competitively inhibits DNA polymerase and results in chain termination after incorporation into the viral DNA
62
Toxicity of Adefovir
Dose-dependent nephrotoxicity, Lactic acidosis, and hepatomegaly
63
Mechanism of action of Interferon alpha
Binds to specific membrane receptors on the cell surface and initiate enzyme induction, suppression of cell proliferation, immunomodulatory activities, and inhibition of viral replication. Following binding to receptors, IFNs activate the JAK-STAT signal-transduction pathway and leads to nuclear translocation of a cellular protein complex that binds to genes containing and IFN-specific response
64
Mechanism of resistance to Interferon alpha
blocking production or activity of selected IFN-inducible antiviral proteins
65
Toxicity to Interferon alpha
Flu-like syndrome, thrombocytopenia, anemia, hypotension, neuropsychiatric, and should not be administered during pregnancy
66
What can interferon alpha do to the immune system?
Modify it
67
What products have longer half-lives, slower clearance, and steadier serum concentrations allowing for less frequent dosing?
Pegylated products
68
Mechanism of action for Ribavirin
Interferes with the synthesis of guanosine triphosphate, inhibits capping of viral mRNA, and inhibits viral RNA-dependent RNA polymerase
69
Toxicity to Ribavirin
Hemolytic anemia, depression, and shouldn't be administered during pregnancy

Drug Mechanisms (9 decks)

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