Antivirals Flashcards
5-iododeoxyuridine and trifluorothymine were early antiviral agents that had poor ______ and were thus too toxic for systemic use, but are still used for topical treatment of ______
poor specificity- inhibited host and viral DNA
used for herpes keratitis
List viruses that can now be treated with antiviral therapies
herpes viruses HCV HBV papillomavirus influenza HIV
All antivirals are ______; they are active only against replicating virus and do not affect latent virus
virustatic
List some drugs that inhibit viral entry or penetration
fusion inhibitors, soluble receptor decoys, antireceptor antibodies, interferons
List some drugs that inhibit release of the viral genome (uncoating)
ion channel blockers, capsid stabilizers
List some drugs that inhibit viral transcription and replication of viral genes
viral DNA and RNA polymerase inhibitors, reverse transcriptase inhibitors, interferons
List some drugs that inhibit translation of viral mRNA into protein
interferons, antisense oligonucleotides
List a drug class that inhibits post-translational modifications
protease inhibitors
List a class of drugs that inhibit assembly of virion components
Interferons
List drugs that inhibit budding and release of virus
Neuraminidase inhibitors, interferons, antiviral antibodies, cytotoxic lymphocytes
Valacyclovir is a prodrug acyclic guanosine nucleoside analogue active against:
HSV-1 and HSV-2
VZV
EBV
Describe the mechanism of action of valacyclovir
Viral thymidine kinase (TK) converts acyclovir into acyclovir monophosphate; the monophosphate is then converted into the triphosphate form by cellular enzymes
Acyclovir triphosphate inhibits viral DNA synthesis by competitive inhibition of viral DNA polymerase and incorporation into the growing viral DNA chain, causing chain termination
What are adverse reactions to valacyclovir?
CNS, GI, nephrotoxicity
What precautions should be noted for use of valacyclovir?
renal insufficiency- dose reduction
What viruses is ganciclovir active against?
CMV (indicated for CMV retinitis)
weak activity against HSV, VZV
Describe the drug ganciclovir
Synthetic acyclic guanosine nucleoside analogue
mainly indicated for CMV retinitis
Describe the mechanism of action of ganciclovir
CMV kinase (UL97 gene) in CMV-infected cells converts ganciclovir to the monophosphate; the monophosphate is then converted into the triphosphate form by cellular enzymes
Ganciclovir triphosphate inhibits viral DNA synthesis by competitively inhibiting viral DNA polymerase and also causing eventual chain termination
________ is a drug that is CMV selective and has weaker activity against HSV and VZV strains
Ganciclovir