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Micro Unit 4 > Antiviral Drugs > Flashcards

Antiviral Drugs Flashcards

1
Q

T/F: There is only one type of antiviral drug in use today?

A

FALSE: there are 4 types as of now - nucleoside analogs, non-nucleosides, protease inhibitors, entry inhibitors

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2
Q

How do antiviral drugs work?

A

they target essential virus functions, host cell intrinsic immunity, activate immune response

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3
Q

What essential virus functions do antivirals target?

A 
1- viral entry
2- viral uncoating 
3- Nucleic acid synthesis
4- assembly of viral particles
5- release of viral particles
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4
Q

What is the mechanism of the nucleoside analogs?

A

they compete for the enzymes in purine and pyrimidine synthesis pathways

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5
Q

T/F: Most antiviral drugs are effective against many different viruses?

A

FALSE: most drugs target functions of only one specific virus (viruses are each too unique for broad spectrum drugs to work)

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6
Q

What does “off target” effect mean in regard to antiviral drugs?

A

off target effects can harm host cells

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7
Q

What is one issue with “on target” drugs directed at viral enzymes?

A

They can be defeated by resistance mutations

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8
Q

T/F: most antiviral drugs have irreversible effects?

A

FALSE: most drugs are reversible = COMPETITIVE INHIBITORS

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9
Q

What does rebound mean in the context of antiviral drugs?

A

Rebound= virus replication resumes when drug is cleared

*because of this, many antiviral treatments are long-term or life-long

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10
Q

Why is drug resistance so prevalent among viruses?

A

high rate of virus replication
high mutation rate (RNA viruses&raquo_space;> DNA viruses)
high selective drug pressure (long-term or multiple tx)
immunosuppressed host cannot clear virus-infected cells

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11
Q

T/F: resistance mutations often exist in a patient before drug treatment

A

TRUE!!

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12
Q

In order to fight resistance to antivirals the infected person may need immunosuppression alleviated, how is this done?

A

If they are on immunosuppressants then the doses may be lowered (ex. steroids, cyclosporin…)

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13
Q

T/F: In order to minimize antiviral resistance, antivirals given should all target the same viral functions?

A

FALSE: combine drugs with DIFFERENT targets:
all HIV pts treated this way
drugs with diff. MOA synergize
lower probability that multiple resistance mutations will be present

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14
Q

Why is it beneficial to target host functions when treating for a viral infection?

A

It is one method used to reduce the probability of antiviral resistance:

  • infected cells may have a unique profile that can be targeted by a drug
  • virus mutations don’t change cellular genes (no resistance possible)
  • some cancer drugs target dividing cells and inhibit viruses
  • MAY BE ASSOC. WITH TOXICITY
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15
Q

When do you treat someone for HSV1/2, or VZV?

A
  • neonates infected with HSV
  • frequent recurrences of HSV1/2
  • complicated HSV infection (encephalitis, global dissemination)
  • eye infection
  • zoster infections w/i 3 days of rash (shingles)
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16
Q

Name this drug: nucleoside analog of guanosine, effective against HSV, inhibits DNA synthesis and viral replication by competing with deoxyguanosine triphosphate for viral DNA polymerase and being incorporated into viral DNA?

A

Acyclovir

17
Q

Ganciclovir treats what?

A

CMV

18
Q

How is ganciclovir similar and different from acyclovir?

A

both are nucleoside analogs of guanosine, similar MOA

-differences: highly toxic (suppresses BM, mutagenic, teratogenic, sever side effects)

19
Q

Who should be treated with ganciclovir?

A

bone marrow and organ transplant pts
immunosuppressed people with active CMV
CMV retinitis

20
Q

List the “broad spectrum” treatments for DNA viruses

A

foscaret

cidofovir

21
Q

Name this drug: Trisodium phosphonoformate, inhibits viral DNA polymerase, effective against all herpesviruses, IV only, renal toxicity

A

foscarnet

22
Q

Decsribe Cidofovir

A

nucleoside analog of cytosie
effective against DNA viruses: herpesvirus, adenovirus, papillomavirus, poxvirus
- IV only
-renal toxicity

23
Q

Are there antivirals specifically designed to treat HBV?

A

No, HBV is treated with drugs designed for HCV and HIV

24
Q

What are the current drug options for treating HBV?

A
  • pegylated interferon alpha
  • entecavir
  • tenofovir disoproxil fumarate
25
Q

Who should be treated for HBV?

A
  • pts with chronic active HBV
  • pts coinfected with HCV and/or HIV
  • pts progressing to cirrhosis, liver failure, hepatocellular carcinoma
26
Q

Who should be treated for influenza?

A
  • severely ill
  • children under 2
  • adults >65
  • pregnant women
  • immunosuppressed
  • anyone suspected of having influenza
27
Q

What are the current antivirals for influenza?

A

zanamivir (relenza), oseltamivir (tamiflu)

both are sialic acid analogs that inhibit viral neuraminidase

28
Q

Ribivarin

A

Nucleoside analog of guanosine

  • oral, IV, and aerosol versions
  • approved for HCV and RSV
29
Q

what are the off label uses of ribivarin?

A

HSV, influenza, SARS, la crosse encephalitis, Nipah encephalitis, lassa fever, hemorrhagic fever with renal syndrome, Crimean-Congo hemorrhagic fever, Bolivian hemorrhagic fever, Hantavirus

30
Q

Postulated MOA for ribivarin

A

inhibition of IMPDH, inhibition of HCV RdRp, RNA mutagenesis

31
Q

Treatments for HCV

A

combo therapy peg-interferon-alpha + ribavarin

32
Q

What are the issues with treating HCV?

A

not all HCV genotypes respond to drugs
-difficult and complicated tx regimen: flu-like sx, anemia, neutropenia, thrombocytopenia, rashes, hair loss, thyroid dysfunction, depression, fatigue, irritability, mania…

33
Q

describe the first HIV antiviral drug

A

AZT= zidovudne, now considered old, nucleoside analog of thymidine, NRTI class = nucleoside reverse transcriptase inhibitor

34
Q

What are the classes of anti-HIV drugs?

A
  • entry inhibitor
  • NRTI (nucleoside/tide Reverse transcription inhibitor)
  • NNRTI (non-nucleoside RTI)
  • Integrase inhibitor
  • protease inhibitor
35
Q

What stage in the HIV life cycle do the NRTI’s and NNRTI’s inhibit?

A

reverse transcription/ replication of genome

36
Q

What stage in the HIV life cycle do the integrase inhibitors affect?

A

integration into host genome

37
Q

What stage in the HIV life cycle do the protease inhibitors affect?

A

processing

38
Q

Liver enzymes are sometimes included in HIV tx, why is this?

A

Cobicistat:

increases the blood levels of all of the antivirals by inhibiting CYP3A4 which breaks down the drugs in the liver

Micro Unit 4 (8 decks)

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