Antiviral Drugs Flashcards

1
Q

describe first, second, and third lines of defense

A

1st: mechanical, chemical, biological barriers
2nd: innate immune response
3rd: adaptive immune response

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2
Q

describe the 3 different kinds of vaccines

A
  • inactivated: genome destroyed, capsid intact
  • attenuated: extremely slow to replicate, “live” viruses
  • genetically engineered: viral proteins produced by yeast cells, concentrated, and purified
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3
Q

6 barriers to finding effective antiviral drugs

A
  • selective toxicity for virus fxns
  • resistance due to rapid mutation
  • intracellular - can’t use non-permeable drugs
  • symptoms usually occur at height of viral replication
  • latency or non-replicating phases hard to target
  • limited capability for rational drug development
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4
Q

which viruses do we have antiviral drugs against?

A
  • herpes simplex virus
  • varicella-zoster virus
  • CMV
  • HIV
  • influenza A and B
  • hepatitis B and C
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5
Q

how do antivirals disrupt enveloped viruses?

A
  • nonoxynol-9, or N9-detergent (emulsify lipid coat)
    - HSV, HIV
  • citric acid
    - Rhinovirus
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6
Q

how do antivirals disrupt viral attachment?

A
  • neutralizing Ab’s that interfere w/ ability to infect
    • interfere w/ receptor binding
    • cause aggregation of virus particles
  • receptor antagonists
  • fusion inhibitors
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7
Q

what is an example of an antiviral receptor antagonist?

A

Maraviroc/Selzentry - CCR antagonist

binds to/changes shape of CCR5 receptor so it is not recognized by gp120 coreceptor binding sites

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8
Q

what is an example of an antiviral fusion inhibitor?

A

Enfuvirtide/Fuzeon - peptide mimic of HR2 region of gp41, inhibiting the action of the viral fusion protein gp41 of HIV

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9
Q

what are two examples of antivirals that disrupt viral uncoating?

A

Adamantanes (M2 inhibitors) - amantadine/symmetrel and Rimantadine/flumadine

  • weak organic bases to treat Influenza A
  • target M2 protein - disrupt H+ transport -> inhibits uncoating
  • well absorbed orally, crosses BBB
  • 90% excreted unchanged
  • low toxicity, some hallucination with amantadine
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10
Q

how do antivirals interfere with nucleic acid synthesis?

A

-nucleoside analogs that inhibit viral polymerase by causing chain termination
nucleoside analogs that cause errors in replication and transcription
-non-nucleoside analogues

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11
Q

general mechanism of action for nucleoside analogues

A
  1. taken up by cells
  2. phosphorylated first by viral enzyme, then twice by cellular enzymes into triphosphate form
    3a. inhibit DNA and RNA polymerase activity, w/ higher affinity for viral enzymes
    3b. incorporated into growing DNA -> abnormal proteins or breakage
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12
Q

acyclovir: other names, what is it used to treat, describe it in terms of structure, in general what does it help with

A

valacyclovir (prodrug), penciclovir (cream), famciclovir (oral)

  • drug used primarily for HSV-1, HSV-2
  • purine mimic of 2’ deoxyguanosine
  • decreased pain, speed healing of sores/blisters in chicken pox, herpes zoster, genital herpes
  • prevent outbreaks of genital herpes
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13
Q

mechanism of action of acyclovir

A
  1. inactive acyclovir activated by phosphorylation of an OH by viral thymidine kinase
  2. host thymidine kinase adds two more phosphates -> active, triphosphate form of drug
  3. drug incorporated into growing DNA chain, but has no 3’ OH, so causes chain termination b/c another nucleotide cannot be added on
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14
Q

why will acyclovir not affect healthy cells?

A

acyclovir must be phosphorylated first by VIRAL enzymes… host enzymes cannot form the monophosphate form, therefore, they will not be affected

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15
Q

ganciclovir: other names, what is it used to treat, describe it in terms of structure, adverse effects, in general what does it help with

A

cytovene/ cymevene/ vitraset

  • active against all herpes viruses including CMV
  • synthetic analogue of 2’-deoxyguanosine
  • still phosphorylated first by viral enzyme, then by cellular
  • AE: bone marrow suppression (leukopenia, thrombocytopenia), CNS effects (headaches, behavioral, psychosis, coma, convulsions)
  • drug of choice for CMV retinitis, pneumonis, colitis
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16
Q

why does acyclovir not work for CMV?

A

CMV does not code for a thymidine kinase

17
Q

axidothymidine: other names, what is it used to treat, describe it in terms of structure, adverse effects, in general what does it help with

A

zidovudine

  • thymidine analogue w/ 3’ azido instead of OH
  • inhibits RT of HIV -> premature termination of DNA chain
  • AE: granulocytopenia, anemia (mostly in AIDS patients), headache, nausea, insomnia, myalgias
18
Q

acyclic nucleoside phosphonates: name two, how are they different from other nucleoside analogues, how do they function, what do they treat

A

cidofovir and tenofovir

  • already have a phosphate -> independent of viral phosphorylation
  • substrates for DNA polymerases or RT
  • decrease amount of HIV in blood
  • cidofovir: CMV, retinitis in AIDs people (but liver damage)
  • tenofovir: HBV, HIV
19
Q

telbivudine: other name, how is it phosphorylated, what is it structurally, what does it do

A

tyzeka

  • synthetic thymidine nucleoside analogue
  • phosphorylated by cellular kinases
  • inhibits HBV DNA polymerase
  • treats HBV
20
Q

what are three antivirals that cause errors in replication and transcription?

A
  • ribavirin
  • trifluorothymidine
  • idoxuridine
21
Q

ribavirin: other names, describe it structurally, how does it act, adverse effects

A

rebetol

  • guanosine analogue w/ incomplete and open base ring
  • must be phosphorylated
  • incorporated into RNA, pairs w/ U or C, inducing mutations in RNA viruses
  • AE: anemia
22
Q

trifluorothymidine: other names, describe it structurally, how does it act, how is it given/what for

A

TFT

  • thymidine analogue
  • CF3 group on U blocks base pairing
  • phosphorylated by cellular enzymes
  • ophthalmic solution or topical treatment for herpes epithelial keratitis
23
Q

idoxuridine: other names, how does it act, what does it treat

A

virasolve

  • substitutes itself for thymidine in viral DNA (transcription continues, but then creates faulty proteins)
  • treats keratoconjunctivitis and keratitis from herpes simplex
  • phosphorylated first by viral OR cellular thymidine kinase (less selective b/w infected vs. healthy cells)