Stahlein Flashcards
herpes virus shape
double stranded DNA
HSV-1 location and infects who
oral herpes
infected as child
HSV-1 ganglion location
trigeminal ganglion
HSV-2 location and infects who
genital herpes
infected as adult or teenager
HSV-2 ganglion location
sacral ganglion
VZV causes what
chickenpox as kids
shingles as reativation in adults
CMV is what
most adults have it but no symptoms, symptoms seen in immunocompromised
retinitis in AIDS pts
acyclovir MOA
competitive inhibitor of viral DNA polymerase
incorporates into DNA
chain terminator
does acyclovir require phosphorylations
yes, three
first by viral enzyme
acyclovir resistance
mutations in viral thymidine kinase and viral DNA polymerase
valacyclovir MOA
competitive inhibitor of viral DNA polymerase
incorporates into DNA to act as chain terminator
valacyclovir metabolism
converted to acyclovir by esterases in intestine and liver after intestinal transport
valacyclovir resistance
mutations in viral thymidine kinase and viral DNA polymerase
penciclovir is active form of what
famciclovir
penciclovir / famciclovir MOA
competitive inhibitor of viral DNA polymerase
chain termination but not immediate
which drug has chain termination but allows short elongation before
penciclovir
famciclovir
acyclovir
valacyclovir
penciclovir
famciclovir
how is famciclovir converted to penciclovir
first pass metabolism
ganciclovir MOA
competitive inhibitor of viral DNA polymerase
chain termination but not immediate
(same as penciclovir)
ganciclovir more active against what
CMV
ganciclovir
ganciclovir toxicity
myelosuppression!
ganciclovir resistance
due to mutations in CMV kinase or CMV DNA polymerase
cross resistance with acyclovir
penciclovir due to viral kinase mutants
why can penciclovir have chain elongation
2 OH groups allow a couple more additions
ganciclovir cross resistance?
mutations in DNA polymerase have cross resistance with foscarnet or cidofovir
NOT for mutations with kinase
valganciclovir is what
prodrug of ganciclovir
used for CMV retinitis
foscarnet MOA
inhibits viral DNA polymerase, RNA polymerase, and HIV reverse transcriptase
blocks pyrophosphate binding site of DNA polymerase
inhibits cleavage of pyrophosphate from dNTPs so new base can’t be added
does foscarnet require phosphorylation?
NO!
foscarnet
foscarnet binding site
binds binding site usually belonging to gamma pyrophosphate which usually helps ass nucleotides on
clinical use of foscarnet
CMV retinitis
use w ganciclovir
foscarnet toxicity
renal toxicity
foscarnet resistance
mutations in DNA polymerase or HIV reverse transcriptasec
cidofovir MOA
competitive inhibitor of viral DNA polymerase and chain terminator
cidofovir is an analog of what
cytosine
cidofovir
cidofovir, phosphorylations?
only needs 2 by cellular kinases
cidofovir highly selective for what
DNA polymerase
cidofovir used for what
CMV
letermovir MOA
inhibits CMV terminase complex by binding pUL56 and preventing packing and cleaving
letermovir
non nucleoside
which of the anti-herpes drugs are chain terminators and incorporated into DNA
acyclovir
valacyclovir
famciclovir
penciclovir
cidofovir
ganciclovir
valganciclovir
which of the anti-herpes drugs are prodrugs
acyclovir
valacyclovir
famciclovir
valganciclovir
influenza virus shape
negative stranded RNA virus
influenza vaccine protects against what
Flu A and B
2 genes that are subtypes of influenza A
hemagglutinin
neuraminidase
how do neuramidase inhibitors work
mimic structure of sialic acid at transition state and stall the enzyme activity
what does neuramidase do
cleave the bond between hemaglutinin and sialic acid to release virus
neuramidase inhibitor drugs
oseltamivir
zanamivir
peramivir
baloxavir MOA
inhibits viral cap snatching of 5’ catch from host mRNA to block transcription and inhibit viral RNA syntheiss and replication
baloxavir interactions
dairy, metals
spectrum of activity of baloxavir
flu A and B
oseltamivir MOA
neuramidase inhibitor
oseltamivir metabolism
prodrug converted to active form by liver esterases
resistance to oseltamivir
mutations in active site of neuramidase
which neuramidase inhibitor has the most resistance
oseltamivir
why does oseltamivir have the most resistance
floppy structure cant fit in the pocket of neuramidase with mutations but zanamivir can fit even with the mutations
zanamivir MOA
neuramidase inhibitor and transition state analog
zanamivr spectrum of acitvity
flu A and B
zanamivir dosage form
inhaler
is zanamivir a prodrug
NO
peramivir MOA
neuramidase inhibitor and transition state analog
peramivir spectrum
flu A and B
hepatitis C shape
small positive stranded RNA virus
HCV life cycle
hep c makes a single polyportein that is cleaved by cellular and viral proteases
- replication complexes are formed
- RNA replication occurs
how do interferons have defense against viruses
induce synthesis of cellular proteins and have antiviral effects
interferon use
used to be primary treatment for Hep B and C
- not absorbed orally
- used in combo with ribavairin
interferon toxicity
flu like symptoms, could cause life threatening side effects
ribavirin is what
guanisine analog
ribavirin MOA
inhibits inosine monophosphate dehydrogenase (IMPDH)
- reduces GTP levels (host enzyme)
direct inhibition of viral RNA polymerase
incorporation into viral RNA
how do protease inhibitors work
mimic the substrate so protease binds and and locked in from being active
- block cleavage of the HCV polyprotein
HCV NS3 protease inhibitors
grazoprevir
voxilaprevir
glecaprevir
-previr class
protease inhibitors NS3
grazoprevir
voxilaprevir
glecaprevir MOA
HCV protease inhibitors
induced fit binding at active site
grazoprevir
voxilaprevir
glecaprevir resistance
mutations at NS3 active site
sofosubir metabolism
prodrug, nucleotide analog
converted to monophosphate by liver enzymes
sofosubir MOA
HCV RNA polymerase inhibitor
incorporated into RNA chain and causes termination
sofosubir resistance
single mutation in active site of HCV RNA polymerase
dasabuvir MOA
non nucleoside RNA polymerase inhibitor NS5B
dasabuvir binding site
palm I site of HCV RNA polymerase (allosteric)
blocks nucleotide incorporation into viral RNA
NS5B inhibitors
sofosbuvir
dasabuvir
NS5A inhibitors
ledipasivir
elbasvir
daclatasvir
velpatasvir
pibrentasvir
ledipasivir
elbasvir
daclatasvir
velpatasvir
pibrentasvir MOA
bind NS5A protein
inhibits viral RNA replication and assem ble or release of infectious viral particles
ledipasivir
elbasvir
daclatasvir
velpatasvir
pibrentasvir resistance to NS5A inhibitors
mutations in first 100 amino acids
1st gen high resistance for single mutations
black box warning for HCV antivirals
Hep B reactivation in pts infected with Hep C if taking a direct acting antiviral without interferons
hep B infection shape
partially double stranded DNA virus
anti retrovirals for Hep B
lamivudine
tenofovir
entecavir
lamivudine MOA
incorporated into viral DNA and causes chain termination due to lack of OH group
tenofovir metabolism
prodrug
only requires two phosphorylatiuions and is stable due to already having a phosphate
tenofovir is an analog of what
adenosine
protease inhibitors - previr drug interasctions
CYP3A4 substrates
weak inhibitors
SARS CoV-2 drugs
remdesivir
nirmatrelvir
molnupiravir
remdisivir MOA
inhibits RNA polymerase
(adenosine analog)
nirmatrelvir MOA
protease inhibitor
peptidomimetic inhibits active site cysteine residue
molnupiravir MOA
polymearse inhibitor and chain terminator
tenofovir
does not have ribose ring
NRTI
lamivudine
sulfur instead of OH
NRTI
emtracitibine
sulfur instead of OH
NRTI
abacavir
double bond instead of OH
NRTI
NRTI MOA
competitive inhibitors of reverse transcriptase
DNA chain terminator
NRTIs
abacavir
lamivudine
emtricitabine
tenofovir
how are NRTIs activated
cellular enzymes phosphorylate
tenofovir alefenamide metabolism
activated once inside the lymphocytes so drug gets right to infected cells
decreased plasma concentration so decreased toxicities like kidney damage
tenofovir alefenamide becomes what
TDF
TAF dose compared to TDF
can use 10 x lower dose
tenofovir AF consideration
only 2 phosphoryaltions
higher lipid levels
NRTIs have a high affinity for what
reverse transcriptase than for DNA polymerases
how do we get resistasnce to NRTIs
NRTIs can’t suppress viral replication 100% so we still have some
we must maintain drug levels above MIC as mutations related to drug conc
which drug should we test for HLAB5701 for before starting
abacavir
could be lethal
non nucleoside RT inhibitors MOA
block RNA and DNA dependent polymerase activities
- bind hydrophobic pocket and confer confirmational change
NNRTIs drug interactions
CYP3A4
NNRTI drugs
efavirenz
nevirapine
etravirine
rilpivirine
do NNRTIs require activation?
no
do mutations that cause resistance to NRTIs confer resistance to NNRTIs?
no they are different
integrase inhibitors MOA
inhibits insertion of HIV DNA into human genome by blocking the strand transfer at the chelating metal level
key structural component of integrase inhibitors that enables them to inhibit
oxygen atoms chelate with the metals
elvitegravir
dolutegravir
bictegravir class
integrase inhibitors
elvitegravir considerations
metabolized by CYP3A4 so taken with cobicistat
HIV protease inhibitors mechanism
peptidomimetics bind protease and prevent it from cleaving further
causes confirmational change in protease
why do we use CYP3A4 inhibitors with proteast inhibitors
PIs are metabolized by CYP3A4 so giving ritonavir with it will boost the levels
what drug can we use for PI boosting
ritonavir to inhibit CYP3A4
HIV protease inhibitor drugs
darunavir
tipranavir
atazanivir
unique features of darunavir
makes extensive hydrogen bonds with protease backbone
inhibits HIV protease dimerization
HIV protease inhiitors bette4r for resistance
darunavir
atazanivir