Antiviral Drugs Flashcards
what are the types of viral treatments?
virucidal (detergents and cryotherapy), immunomodulatory and antivirals
what are the main classes of antivirals?
nucleoside analogs, non nucleoside analogs, protease inhibitors and entry inhibitors
what is the most common step of the viral life cycle that is inhibited by antivirals?
nucleic acid synthesis
which drug is most commonly used to modify the host cell defenses and what are its downsides?
pegylated interferon, it can have very bad side effects
are there broad spectrum antivirals? if not, why?
there are a few but most are very specific (evolved separately)
what are “nucs”?
antivirals that are nucleoside analogs. compete for enzymes in purine and pyrimidine synthesis pathways
what is the most common mechanism for antiviral drugs? what is the downside of this?
most are reversible competitive inibitors. the virus will rebound once the drug is cleared
what factors favor the emergence of viral resistance?
high rate of replication, high mutation rate, high selective drug pressure (long term/multiple treatments) and an immunosupressed host
how is resistance to antivirals countered?
alleviating immunosupression, combining drugs with different targets, and targeting host cell functions that will not be impacted by viral mutations
who, of the people with HSV1, HSV2 and VSV should be treated?
neonates, people with frequent recurrences of HSV, complicated HSV infections, and people with zoster within 3 days of appearance
describe acyclovir and its mechanism of action
it is a thymine analog without the pentane sugar ring. it is phosphorylated by viral TK and incorporated into DNA instead of dTTP.
what infections should Acyclovir be used against?
HSV 1 and 2 (not zoster)
describe Ganciclovir and its mechanism of action
it is a guanine analog that has similar mechanism to Acyclovir (incorporated into DNA)
why does Ganciclovir have such bad side effects?
It can be utilized by human cells as well. it is highly mutagenic
who should be treated with Ganciclovir?
organ transplant patients, immunosuppressed people with CMV and people with CMV retinitis
what are the two broad spectrum treatments for DNA viruses?
Foscarnet and Cidofovir
what is the mechanism of Foscarnet, what is it effective against and what are its disadvantages?
effective against all herpesviruses by inhibiting viral DNA polymerase. it can only be administered IV and it is toxic to the kidneys
what is Cidofovir effective against, what is its mechanism and what are its disadvantages?
It is effective against a variety of DNA viruses. It is a cytosine analog and it is IV only with kidney toxicity
What are the current treatment for Hep B virus and what other diseases do they treat?
pegylated interferon, entecavir and tenofovir. Treat HCV and HIV also
which HBV patients should be treated?
patients with chronic, active HBV, people coinfected with HCV or HIV, and people who are progressing to liver damage and failure
what are the treatments for Influenza and how do they work?
Relenza (inhaled) and tamiflu. work by keeping budding virions attached to the cell
who should be treated for Influenza?
anyone suspected of having it
What is the mechanism of Ribavirin
glucoside analog that prevents many pathways to create a defective virus
what is Ribavirin used to treat?
it is approved for HCV and RSV but is used off-label for many other viruses
How do you treat Hep C and why is compliance low?
pegylated interferon with ribavirin and it is painful with many side effects
what is pegylated interferon?
it is interferon that is slowly released into the body
what is AZT and why is it no longer used?
it is the first HIV drug similar to Acyclovir (reverse transcriptase inhibitor) that most strains are now resistant to.
what is the current treatment strategy for HIV?
drug combinations of four drugs
what are the classes of anti HIV drugs?
entry inhibitor, nucleoside reverse transcriptase inhibitor, non nucleoside reverse transcriptase inhibitor, integrase inhibitor and protease inhibitors
what is cobicstat?
a drug enhancer that inhibits liver break down
what is the new strategy for HIV treatment?
fewer pills with a drug enhancer
