antiviral pharmacology Flashcards
what is the mechanism of action of acyclovir?
competes with deoxyGTP for viral DNA polimerase and becomes incorporated into the replicating viral DNA chain ==> causes DNA SYNTHESIS TERMINATION
what type of anti-viral drug is monophosphorilated by vial thymidine kinase in infected cells and then activated to a triphosphate form by host cellular kinases in order to be inserted into newly synthesizing DNA?
guanisine analogues
acyclovir
famiciclovir
valcycloive
what drug can be used for CMV in immunocompromized pts?
ganiciclovir or it’s prodrug (valganiciclovir) which has better bioavailability
what are the major side effects of the guanisine analgogues (e.g. acyclovir)?
obstructive crystalline nephropathy and acute renal failure
what can be used to prevent renal toxicitiy from acyclovir?
maintain hydration
what is the major side effect of ganciclovir?
bone marrow suppression and renal toxicity
What is the mechanisms of resistance to acyclivir?
mutated viral thymidine kinase
what is the mechanism of action of foscarnet?
FOScarnet inhibits viral DNA/RNA polimerase and also inhibits HIV reverse transcriptase by competing for pyroFOSphate binding site
used for acyclovir-resistant HSV
what is hte mechanism of resistance for foscarnet?
FOScarnet work by allosterically inhibiting viral polymerases (binds to pyroFOSphate binding site), so virsuses with mutated DNA polymerases can be resistant
What are the main side effects of foscarnet?
nephrotoxicity, electrolite imbalances, SEIZURES!
What antiviral drug preferentially inhibits viral DNA polimerase, does not require phosphorilation by viral kinase, causes nephrotoxicity and is not foscarnet?
cidofovir/tenovir
what should be given with cidofovir/tenovir to prevent toxicity?
probenecid + IV saline
*probenecid inhibits organic anion transport in the renal proximal tubule
What is the mechanism of the drug you would give a pt with acute changes in mental status, seizures, headache, CSF with hemorrhagic lymphocytic pleocytosis with incraesed protein and normal glucose?
MRI shows abnormal MRI signal in bilateral tempral lobes?
pt has HSV encephalitis
give acyclovir - guanisine nucleotide analgogue - competes for viral DNA polimerase for incorporation into replicating DNA and causes chain sysnthesis termination. Must be activated by viral thymidine kinase then phosphorilated to triphosphate form by host cell enzymes
