Antivirals (O'Brien) Flashcards
Anti-herpes/CMV drugs (non-HIV)
acyclovir, ganciclovir, foscarnet
Anti-influenza drugs (non-HIV)
amantidine, oseltamivir, zanamivir
Acyclovir mechanism
Viral thymidine kinase phos. acyclovir –> monophosphate –> more phos. happens with our thymidine kinase –> blocks DNA synthesis via competitive inhibition of viral DNA synthesis
How much phosphorylations does acyclovir undergo
3 (first one is viral thymidine kinase)
How is acyclovir administered
topically and IV
Is acyclovir a first line agent?
indeed!
What toxicity should you worry about for acyclovir?
renal, interactions
acyclovir resistance mechanisms
alteration in viral thymidine kinase
What drug can you give if pt. is resistant to acyclovir?
foscarnet
Anti-CMV agents
ganciclovir, foscarnet
ganciclovir mechanism
acyclic guanosine analog; first phos catalyzed by CMV kinase
Can ganciclovir be given orally?
no!
Ganciclovir active against
CMV (100x>acyclovir)
This is used as treatment/prophylaxis for CMV post-transplantation
ganciclovir
Ganciclovir toxicity
myelosuppression
Foscarnet mechanism of actions
inhibits viral DNA and RNA polymerase, HIV RT
Does foscarnet require phos?
No!
How is foscarnet administered
IV only
Foscarnet used in strains resistant to…
acyclovir
Foscarnet toxicities
renal; hyperphosphatemia, hypokalemia/calcemia/magnesemia
T:F - Anti-influenza agents must be given quickly after onset of symptoms
true
Oseltamivir (tamiflu, oral) and zanamivir (inhaled) are ______ inhibitors
neuraminidase inhibitors (analogs of sialic acid
Oseltamivir (tamiflu, oral) and zanamivir (inhaled) have activity against influenza…
A and B
Zanamivir is useful against ______-resistance strains
oseltamivir
Reverse Transcriptase Inhibitors (RTIs)
RTIs
Nucleoside: abacavir, emtricitibine/lamivudine
Non-nucleoside: efavirenz
Nucleotide: tenofovir
HIV protease inhibitors: atazanavir, darunavir, ritonavir
Fusion, entry, integration inhibitors: enfuvirtide, maraviroc, dolutegravir
What was wrong with AZT?
retroviral replication is error prone and increase mutation frequency and increase resistance
What is the standard of care of HIV?
combo therapy
How are drugs selected for HIV?
based on pt strain resistance (genotype strain for mutations in RT and protease genes for mutations that can lead to resistance
NRTIs=nucleoside reverse transcriptase inhibitors act by…
competitive inhib of RT and incorporation into viral DNA
How are NRTIs activated?
cellular phosphorylation to triphosphate
How does NRTI resistance occur?
mutations in viral RT
NRTI toxicity
lactic acidosis w/ hepatic steatosis (life-threatening) –> due to NRTI-mediated inhib of mitochon fn (causes build-up of triglycerides = hepatic steatosis) –> due to lack of specificity
Abacavir is a ____
reverse transcriptase inhib
Abacavir toxicity (2)
myocardial infarction (caution exercised in CV disease; potentially increases platelet aggregation)
hypersensitivity rxn (can be fatal and with HLAB5701 should never take abacavir)
Lamivudine and emtricitabine are ______ analogs and are used in ____ treatment
- cytosine analog
- used in HBV treatment
Emtricitabine is a fluorinated analog and is favored because____
longer half life and once daily dosing
Truvada is a combo of
emtricitabine and tenofovir
What does tenofovir do?
nucleotide analog of adenosine
Does tenofovir require phosphorylation?
No! nucleoTIDE
Tenofovir mech of action
competitively inhib HIV RT - chain termination after incorporation into DNA
Tenofovir is coadministered w….
emtricitabine as a first-line RIT backbone therapy
Tenofovir toxicity
renal accumulation: tubular necrosis, renal failure, Fanconi’s Syndrome
Efavirenz is a ____
non-nucleoside RTI
Efavirenz binds___and inhibits____
directly to HIV-1 RT and inhibits RNA and DNA-dependent DNA polym activity
What kind of inhibitor is efavirenz?
allosteric (NRTIs are competitive)
What limits the use of efavirenz?
extensive metabolism/induction via CYP3A4
Efavirenz toxicity
nightmares/psychiatric disturbances (at start then resolve)
HIV protease inhibitors are pepitdomimetics which means they…
mimic peptides and inhibit proteolytic cleavage
HIV protease inhibitors toxicity
redistribution and accumulation of body fat (lipodystrophy)
increased triglycerides/LDL
Ritonavir inhibitor of CYP3A4; used with other PIs to increase their serum levels, which means…
less frequent dosing, more tolerability (“boosting”)
Ritonavir toxicity
increase triglycerides/LDL; elevated serum aminotransferase levels
Name the three HIV protease inhibitors
ritonavir; atazanavir; darunavir
Maraviroc is a…
entry inhibitor/CCR5 receptor antagonist
Maraviroc binds…
selectively to CCR5
Maraviroc used in…
HIV-1 strains resistant to other drugs
Enfuvirtide is a…
fusion inhibitor
Enfuvirtide binds to…
gp41
Enfuvirtide is given by…
subq injection (peptide)
What is the treatment for experienced HIV pt w/ ongoing HIV replication?
enfuvirtide
Dolutegravir is a….
integrase strand transfer inhibitor (INSTIs)
Dolutegravir inhibits…
viral DNA strand integration in host genome
Dolutegravir appears effective in HIV that is…
resistant to other INSTIs