Antivirals

Question 1

why is acyclovir more selectively toxic than other antivirals?

Answer 1

• it is activated by viral kinases

- so you only get the drug activated in cells that are infected w/ the virus you are going after

Question 2

what 3 viruses can you use acyclovir against?

Answer 2

VZV, HSV, EBV

Question 3

what are 2 indications for valacyclovir?

Answer 3

• recurrent genital herpes

- zoster infections

Question 4

2 indications for famciclovir?

Answer 4

• acute herpes zoster

- suppression of recurrent genital herpes

Question 5

herpes encephalitis: early symptoms and DOC

Answer 5

• acute onset of fever, headache, decreased consciousness and seizures
• DOC = acyclovir

Question 6

how is gancyclovir metabolized to active form inside host cell?

Answer 6

• acts as an antimetabolite
• first phosphorylated by viral and then by cellular kinases; then forms a nucleotide that inhibits DNS polymerase of CMV

Question 7

how does cidofovir have selective toxicity?

Answer 7

• 1000x more effective against DNA polymerases of viruses like HSV than against DNA polymerase of host cell

Question 8

what is unique about metabolism requirement of foscarnet?

Answer 8

• it inhibits viral DNA polymerase, RNA polymerase or HIV RT directly
• does not require activation by phosphorylation

Question 9

viruses attacked by foscarnet? (7 of them)

Answer 9

CMV
HSV
VZV
EBV
HHV-6
HBV
HIV

Question 10

CDC guidelines for tx of influenze in adults

Answer 10

• zanamivir if 7+ yo
• aseltamivir if 1+ yo
• amatadinei for influenza A in age 1+
• rimantadine for influenza A in adults only

Question 11

MOA of neurominidaze inhibitors (zanamivir and aseltamivir)

Answer 11

• they inhibit viral cleavage of sialic acid

- so they inhibit the release of newly formed viruses

Question 12

sote of action for palivizumab

Answer 12

• binds to fusion (F) protein of RSV = outside the coating of the virus
• keeps the virus from attaching to and entering host cell i.e. reducing replication and spread of RSV

Question 13

dosing and timing of palivizumab tx for RSV

Answer 13

• 15mg/kg IM monthly
• up to 5 doses during RSV season w/ 1st dose just prior to season
• kinetics: half-life = 13-27d (about the half-life of human IgG); onset w/in 48h

Question 14

who should avoid contact w/ people receiving ribavirin and why?

Answer 14

• health care personnel (drug disperses in immediate bedside area after administration)
• prego women (teratogenic)
• adverse effects = headache, conjunctivitis, rhinitis, nausea, rash, dizziness, lacrimation, pharyngitis