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Flashcards in 08 Anti-Viral Agents Louie Deck (41):
1

What are the Viral Entry Inhibitors currently available?

EnFuvirtide (CD4 blocker). Maraviroc (CCR5 Antagonist)

2

What is the problem with monotherapy of EnFuvirtide for HIV?

Very quick resistance occurs

3

How does Maraviroc (Selzentry) work?

Competitively binds to CCR5, preventing an interaction with GP120. It is a "chemokine receptor antagonist"

4

What is Maraviroc (Selzentry) indicated for?

Indicated for treatment-experienced adult patients infected with only CCR5-tropic HIV-1 detectable, who have evidence of viral replication and HIV-1 strains resistant to multiple antiretroviral agents

5

What is Ibalizumab?

A novel humanized monoclonal antibody (Mab) binding to a conformational epitope on CD4, blocking entry to HIV-1. In Phase II right now

6

What did the IV Ibalizumab Phase 2b study results show?

Favorable data indicating efficacy and drug will continue in development

7

What are the NRTIs that are Dideoxynucleoside Analogs?

Stavudine. Lamivudine. Didanosine. Zidovudine. Emtricitabine. Abacavir. On all of these, the 3' Hydroxyl group is important for elongation

8

What are the steps in Intracellular Transport of Nucleosides?

Dideoxy Nucleoside (ddN) is brought in through a channel (ENT2). Once inside, it interacts with kinase to become ddN-TP. This can then either bind to RT (termination of vDNA), go into the mitochondria (causes toxicity, Lactic Acidemia), or go into the Nucleus

9

How do cells get ride of ddN?

Once converted to ddN-MP it can actually get pumped out by the MRP-2, -4, or -5 pumps

10

Why is Nucleoside therapy for Men and Women different?

The ENT2 transporter is also used for folic acid, so there are more of them in women. This causes women to have more ADRs, but also better remission rates

11

What is the benefit of Acyclic Nucleoside Analogs?

No ribose ring, avoids enzymes that cleave them, longer T1/2

12

What are some of the Acyclic Nucleoside Analogs?

Acyclovir. Ganciclovir. Penciclovir. Cidovovir, Adefovir, Tenofovir

13

Which Acyclic Nucleoside Analogs come with a phosphate group already attached?

Cidofovir. Adefovir. Tenofovir. This phosphate group causes them to be highly renally toxic, can also lead to osteoporosis (since calcium will be excreted along with the phosphate group)

14

What is Ganciclovir used for?

CMV. Active against herpes viruses but especially cytomegalovirus (CMV) infections, which typically cause retinitis, and may cause pneumonia, colitis, esophagitis, and hepatitis in immunocompromised patients

15

What is Cidofovir used for?

Synthetic acyclic purine nucleotide analog of cytosine nucleoside when phosphorylated to the diphosphate, inhibits CMV DNA polymerase and blocking viral replication. Disphosphate has 2-3d T1/2. Indicated for treatment of CMV retinitis

16

What are the NNRTIs used?

Delavirdine. Efavirenz. Etravine. Nevirapine

17

Which NNRTI is a potent CYP3A INHIBITOR?

Delavirdine. All others are inducers

18

What is a common ADR with all NNRTIs?

Rash

19

Which NNRTIs cause Hepatotoxicity?

Efavirenz. Etravine. Nevirapine. The only one that doesn't is Delavirdine

20

What is the 2nd Gen NNRTI?

Etravirine. Resistance to other NNRTIs does not seem to confer resistance to Etravirine. Etravirine, in combination therapy, is indicated for the treatment of HIV Type 1

21

Rilpivirine is a new NNRTI being looked at, why is it dosed 25mg in study results?

At 100mg/day it started showing signs of QT Prolongation

22

What are the Protease Inhibitors used?

Indinavir. Sawuinavir. Ritonavir. Nelfinavir. Indinavir. Atazanavir

23

What does the inhibition of Integrase cause?

Strand Transfer Shifts the fate of HIV-1 DNA resulting in an irreversible block to infection. Dead-end products = cell death

24

What are the Integrase Inhibitors in advanced clinical developed?

Raltegravir. Elvitegravir

25

What did a trial conclude when looking at the effect of Dolutegravir on actual GFR and CrCl in healthy subjects?

DTG has no effect on actual GFR. DTG decreases eGFR and CrCl via effect on proximal renal tubular excretion of creatinine, similar to cobicistat

26

What is the goal of Zinc Finger Gene Therapy?

Create a modification to CCR5 co-receptor. Persons with the delta 32 deletion of CCR5 are highly resistant to HIV infection. Zinc Finger Nucleases (ZFNs) are "designer restriction endonucleases" which cleave an area between two CCR5 binding domains. This in turn introduces a DNA break that causes permanent CCR5 co-receptor modification in target cells

27

What is Amantadine (Symmetrel)?

Prevention/treatment of Influenza A Virus (not B). Prevention has efficacy of ~70%. CNS effects limit wide use

28

What is the MOA of Amantadine?

It appears to be VIRUSTATIC by preventing uncoating of virus particles, leading to no viral replication and no infection (ideally). It affects maturation of Influenza HA Glycoprotein in trans-Golgi network

29

What is Rimantadine?

Same as Amantadine, but with fewer ADRs

30

What do Neuraminidase Inhibitors do?

Neurominidase breaks the bond that holds new virus particles to the outside of an infected cell by cleaving sialic acid from the cell surface. This releases new viruses that can infect other cells and spread infection. Neuraminidase inhibitors prevent viral cleavage of sialic acid preventing new virus particles from being released, thereby limiting the spread of infection

31

What are the Neuraminidase inhibitors used?

Oseltamivir and Zanamivir

32

What are the common drugs used for HCV?

PegIFN and RBV

33

How is PegIFN dosed for HCV?

1.5ug/kg weekly

34

What is the range that RBV is dosed for HCV?

800-1400mg daily

35

What are the difference classes of Interferons?

a, B, and y. Each distinct. Different producer cells, inducers, and biologic effects. IFN-a and -B are produced by nearly all cells in response to invasion. Only INF-a has been approved for viral treatment. IFN-y only produced by T cells and NK cells

36

What is the MOA of IFN?

Induces changes in the infected or exposed cell to promote resistance to the virus. Induces several enzyme activities that promote an antiviral state

37

Peginterferons vs. Interferons, what is the rationale for pegylation?

Reduces rate of absorption and clearance. Lower immunogenicity. Maintains higher steady state --> increased viral response

38

What is Ribavirin?

Active against many DNA/RNA viruses and highly active against influenza A and B, but is only approved for treating RSV in infants and young children by aerosol and Hep C together with interferon

39

What are the characteristics of the new target: NS3 Protease?

Hepatitis C RNA encodes for a polyprotein that is 3,000 AA long. This is cleaved by viral and host proteases to form structural and nonstructural proteins. The Nonstructural (NS) proteins are further processed by two viral proteases, NS2/3 and NS3

40

What are the two types of NS3 Protease Inhibitors?

a-Ketoamides (form a reversible covalent bond with serine in the active site). Competitive, noncovalent inhibitors (aim to bind more strongly to active site than substrate through noncovalent interactions)

41

What is needed for NS3 Protease to be active?

In order to be activated it must be bound to an NS4a cofactor