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D&D Infectious Disease FINAL > Pharm - Antiviral Drugs Part 2 > Flashcards

Pharm - Antiviral Drugs Part 2 Flashcards

1
Q

another name for viral thymidine kinase

A

viral UL97

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2
Q

ganciclovir is a ___ ___ analog

A

acyclic guanosine

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3
Q

does ganiciclovir need the viral enzyme?

A

yes
needed for the initial monophosphorylation

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4
Q

ganciclovir has 100x greater affinity for ___ than acyclovir

A

CMV

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5
Q

2 resistance mechanisms for ganciclovir

A
  1. mutation in UL97 kinase
  2. mutation in UL54 (viral DNA polymerase)
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6
Q

3 main AE of ganciclovir

which 2 are rare

A

rare - CNS and hepatotoxicity

MYELOSUPPRESSION - dose-dependent toxicity

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7
Q

true or false

UL54 mutation gives cross resistance with other drugs

A

TRUE

this affects the viral DNA polymerase

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8
Q

prodrug of ganciclovir

A

valgancyclovir

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9
Q

true or false

foscarnet is a nucleotide

A

FALSE

does not have a base, but DOES have phosphate and bypasses first step with viral thymidine kinase

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10
Q

chemically, foscarnet is…..

A

phosphonoformic acid

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11
Q

structurally, what does foscarnet mimic

A

inorganic pyrophosphate

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12
Q

which viruses can foscarnet inhibit and how

A

BOTH HSV and HIV!!!!

-inhibits herpes DNA and RNA polymerase
-inhibits HIV reverse transcriptase

does so by BLOCKING THE PYROPHOSPHATE BINDING SITE ON THE VIRAL DNA POLYMERASE

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13
Q

true or false

foscarnet is a prodrug

A

true

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14
Q

how is foscarnet administered and why

A

ONLY IV

it is small, but too polar for oral use - not good bioavailability

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15
Q

where is foscarnet deposited?

does it distribute well in CSF?

A

deposits in bones and distributed well in the CSF

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16
Q

name 2 things that foscarnet can be used for

A

-end organ CMV that is ganciclovir resistant

-HSV and VZV when acyclovir resistant

bc both ganciclovir and acyclovir need the 1st step and it’s mutated, but foscarnet does not!!!

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17
Q

resistance mechanism for foscarnet

A

point mutations in viral DNA polymerase
(happens with chronic administration)

if HIV - mutations in reverse transcriptase

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18
Q

true or false

resistance to acyclovir also means resistance to foscarnet, but not vice versa

A

FALSE - other way around

foscarnet CAN be used for acyclovir resistance bc it bypasses 1st step

however, if there is resistance to foscarnet that means there is mutations in DNA polymerase and acyclovir cannot work either

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19
Q

2 AE of foscarnet

A

nephrotoxicity

Ca2+ and K+ alterations

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20
Q

foscarnet is contraindicated with what drugs and why

A

other nephrotixic drugs like amphotericin B and aminoglycosides

too much nephrotoxicity

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21
Q

Cidofovir is a ____ analog

A

cytosine

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22
Q

does cidofovir need viral thymidine kinase?

A

NO

cidoFOvir
has a phosphate group already

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23
Q

true or false

cidofovir IS active against thymidine kinase mutants

A

TRUE

does not need 1st step - already a monophosphate

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24
Q

true or false

cidovofir has broad activity against a lot of viruses

A

true

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25
Q

AE cidoofovir

A

nephrotoxic

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26
Q

major treatment in which cidofovir is used

A

CMV retinitis

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27
Q

when an antiviral is converted into triphosphate, what does this allow the drug to do

A

competitively inhibit viral DNA polymerase and stop viral DNA synthesis OR incorporate into viral DNA chain and cause chain termination

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28
Q

another name for spanish flu

A

avian flu

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29
Q

in flu viruses, where do the periodic mutations occur?

A

in neuraminidase and hemagglutin

ie - H1N1 for spanish flu

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30
Q

pandemic vs epidemic vs endemic

A

endemic - restricted to particular region

epidemic - new cases appear in a given population during a given period, at a rate that exceeds what is “expected” based on epidemiology

pandemic - outbreak of infectious disease that has spread throughout a very large region or even globally

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31
Q

influenza is what kind of virus

A

orthomyxovirus
RNA (negative sense)
single strand
helical and enveloped

32
Q

the core proteins for influenza can be…..

A

A B or C

33
Q

what 2 species can influenza be

A

swine or avian

34
Q

how many H and N subtypes for influenza

A

16 H
9N

35
Q

2009 swine flu pandemic had what surface proteins

A

H1N1 (similar to 1918 spanish flu

36
Q

explain antigenic drift for influenza virus

A

the antibodies to hemagglutinin bind to it and block the virus from binding to the host cell

HOWEVER, antigenic drift occurs when mutations ALTER hemagglutinin and the neutralizing antibody can no longer bind to it

virus can now bind the host cell and infect it

37
Q

explain anitgenic SHIFT

A

when an avian and human virus come together, they undergo recombination to produce NEW GENETIC SEGMENTS

leads to new viruses and potential pandemic

38
Q

do avian viruses directly infect humans

A

NO - very rare

avians have a2-3 subtypes and humans have a2-6

only swines can infect humans ( havea2-6)

39
Q

what is the function of M2

A

ion channel that is required for uncoating – open the envelope and allow the nucleic acid to go into the nucleus of the host cell

40
Q

function HA (hemagglutinin)

A

allows for viral attachment to host cell membranes and membrane fusion

41
Q

function NA (neuraminidase)

A

cleaves sialic acid on the surface of host cells, allowing for new viruses to be released

prevents aggregation of the new viruses

42
Q

what is PA and what is proposed function

A

acidic polymerase

function is unknown

43
Q

just by looking at the name, how can you tell if something is a neuraminidase inhibitor

A

“mivir”

44
Q

name 3 neuraminidase inhibitors

A

oseltamivir
zanamivir
peramivir

45
Q

all 3 NA inhibitors are analogs of what?

A

sialic acid

46
Q

explain how viruses are able to leave the host cell and reinfect others (without an NA inhibitor)

A

mucin forms a barrier for microbes in the respiratory tract. however, mucin is rich in sialic acid, and viral neuraminidase REMOVES THIS SIALIC ACID which helps the virus to penetrate the mucin and leave the cell to reinfect others

47
Q

“the snipper”

A

neuraminidase – removes sialic acid

48
Q

true or false

oseltamivir is a sialic acid analog

A

true

49
Q

what does oseltamivir inhibit

A

neuraminidase

50
Q

HOW does oseltamivir inhibit neuraminidase (ie - irreversible/reversible competitive/noncompetitive)

A

reversible and competitive

(structurally mimics sialic acid)

51
Q

as mentioned, oseltamivir is an NA inhibitor
how does this prevent new viral release?

A

the virus will be trapped on the membrane, and all the new viruses will aggregate and can’t get released from the infected cell and reinfect others

52
Q

oseltamivir resistance

A

mutations in hemagglutinin or neuraminidase

53
Q

true or false

oseltamivir is only active vs influenza A

A

FALSE

influenza a and b

54
Q

oseltamivir is active against _____ resistant influenza

A

amantadine

55
Q

WHEN must oseltamivir be administered and why

A

within 48 hours of onset

will not work if you give too late because the new viruses have already been released and are infecting other cells

56
Q

how long is oseltamivir given and why?
how is it good vs the flu

A

5 days - want to make sure cover the entire viral cycle

decreases influenza symptoms, shedding, transmission, and complications

57
Q

**interaction between oseltamivir and probenecid

A

probenecid will increase the plasma half life of oseltamivir

58
Q

counseling point for oseltamivir

A

take with food to decrease unwanted GI side effecys

59
Q

any side effects oseltamavir?

A

not really significant

NVD, fatique
in japan neuropsych events were reported

60
Q

zanamivir mechanism and route of administration

A

inhalation

same MOA as oseltamavir - NA inhibitor

61
Q

of the 3 NA inhibitors, which is considered the “best” route of administration for treating the flu?

A

inhalation (zanamivir) because it’s a respiratory virus

zanamivir has 1000x IC50 values for NA

also, gives fast onset and avoids 1st pass

62
Q

what is peramivir and how is it administered

A

a neuraminidase inhibitor for flu

given by IV infusion for min of 15 minutes

63
Q

explain what type of patient would be indicated to receive peramivir

A

18 years and older who have acute uncomplicated influenza who have been symptomatic for NO MORE THAN 2 days (same as other NA inhibitors)

64
Q

amantadine and rimantidine mechanism

A

binds and blocks viral M2 channel (which normally is open to allow the influx of H ions into the vesicle with the virus). this prevents the uncoating of the virus. and release from the endosome and into the extracellular matrix to infect other cells

65
Q

true or false

amantadine/rimantadine are ONLY active against influenza A

A

true

66
Q

which is more active - rimantadine or amantadine

A

rimantadine

67
Q

compare the t1/2 of amantadine/rimantadine with other anti influenza drugs

A

a lot longer than others
like 12-36 hours

68
Q

some major disadvantages of amantadine/rimantadine (not really used anymore)

A

VERY HIGH RESISTANCE PROFILE

lot of AE like GI effects, CNS effects (bc small molecules - nervousness, insomnia, affects dopamine system, deliruym, seizure, etc)

also CONTRAINDICATED IN PREGNANT WOMEN

69
Q

true or false

amantadine cannot be given to a pregnant person

A

true

70
Q

name of the anti influenza drug that is not an NA inhibitor or M2 channel blocker

A

baloxavir

71
Q

true or false

baloxavir is not a prodrug

A

FALSE - it is

baloxavir marboxil is converted by hydrolysis to baloxavir

72
Q

how is baloxavir administered and what is its mechanism??

A

SINGLE DOSE TREATMENT

it inhibits the endonuclease activity of the polymerase acidic protein, which is an enzyme that’s part of viral RNA polymerase.

thus, inhibits viral gene transcription and hence inhibits the replication of new influenza virus

73
Q

baloxavir resistance

A

amino acid substitutions in the PA (polymerase acidic) protein

74
Q

counseling point for baloxavir

A

DO NOT GIVE WITH MILK OR ANTACIDS!! absorption prevented bc of diketo acid

also, metabolized by CYP3A4 so potentil DDI

75
Q

dosage form baloxavir and what age is it indicated for

A

oral tablets
12 years or older

76
Q
A

D&D Infectious Disease FINAL (21 decks)

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