Antiviral drugs Flashcards
Docosanol/”Abreva”
Over the counter cold sore medication (anti-herpes)
Blocks virus entry
Reduces healing time by ~1 day
What is valtrex?
Val-acyclovir and Val-gangcyclovir
Val is added to improve bioavailability
Cleavage by esterases results in active drug formation
How does acyclovir act selectively on herpes infected cells?
Acyclovir is activated by a herpes thymidine kinase enzyme in the cytoplasm of infected cells
It also requires herpes DNA polymerase to insert into replicating DNA and cause chain termination
What class of drugs do acyclovir and gancyclovir interact with?
Antibiotics
How does the specitrum of activity of gancyclovir differ from acyclovir?
Gancyclovir treats CMV, HHV6 and 8 as well as EBV
Acyclovir treats HSV
What adverse effects are associated with gancyclovir
Bone marrow suppression
Rash, diarrhea, nausea, vomiting
Rarely, neurotoxicity
What is foscarnet?
An analog of pyrophosphate that inhibits pyrophosphate binding on viral DNA polymerase
Foscarnet has broad coverage of the herpes viruses
Useful for resistance to acyclovir/gancyclovir
What adverse effect is associated with foscarnet?
Nephrotoxicity due to accumulation of foscarnet crystals in the glomeruli
Electrolyte disturbances
Myelosuppresion & anemia
What is the mechanism of action of pritelivir?
Anti-HSV medication that inhibits helicase-primase to block viral DNA replication
What class of drugs is used to treat HCV?
Directing-acting antivirals (DAAs) to competitively inhibit viral protease (NS3/4), viral phosphoprotein (NS5A) and viral RNA polymerase (NS5B)
What is the mechanism of action of Ribavirin?
Deplete GTP pools, directly block viral RNA polymerase and induce catastrophic errors during viral replication, trigger antiviral T cell responses
What infections are treated with Ribavirin?
HCV
RSV
Ribavirin should be used in combination with what?
Ribavirin is used in conjunction with pegylated IFN
What is the mechanism of action of PegIFN?
Stimulates host antiviral immunity
Adverse effects of PegIFN
Severe flu-like symptoms
Depression
Caution with cirrhosis patients
What is the difference in recommendation for HBV therapy between HBeAg- and HBeAg+ infecitions
HBeAg- is less infectious, so only treated if viral load is higher (>10^5) compared to HBeAg+, which is treated at lower levels (>10^4)
What drugs are available for pharmacologic management of HBV?
PegIFN
Entecavir - guanosine analog
Tenofovir - adenosine analog
What is the mechanism of action of entecavir?
Inhibits HBV DNA priming, reverse transcriptase and DNA polymerase
Adverse effects of entecavir
Lactic acidosis
Rebound hepatitis
Drug interactions with entecavir
Don’t use in conjunction with HAART for HIV
What drug is used to treat HBV and HIV? How does it work?
Tenofovir
Converted to nucleoside analog which gets phosphorylated and blocks viral DNA polymerase
Drug interactions of tenofovir can cause what problems
renal toxicity
lactic acidosis
Mechanism of action of amantadine
Inhibits influenza A virus entry by plugging the M2 ion channel, thus preventing protons from entering the virus
RNA will not release from virion proteins and uncoating is prevented
What is the main problem with amantadine/rimantadine?
Drug resistance has limited clinical utility
