Antivirals Flashcards
Clinical use of oseltamivir and zanamivir
Treat and prevent influenza A&B
Mech of oseltamivir & zanamivir?
Inhibit neuraminidase (influenza) and dec release of progeny virus
Clinical use of ribavirin?
RSV & chronic Hep C
Mech of ribavirin
Inhibits guanine nucleotide synthesis by competitively inhibiting IMP dehydrogenase
Ribavirin toxicity
Hemolytic anemia
Severe teratogen
Mech of acyclovir
Monophosphorylated by HSV/VZV thymidine kinase.
Guanosine analogue
Triphosphate formed by cellular enzymes
Preferentially inhibits viral DNA polymerase by chain termination
Clinical use of acyclovir
HSV & VZV (not latent forms)
Weak activity against EBV, none against CMV
MC used for HSV-induced mucocutaneous and genital lesions, and encephalitis.
Prophylaxis if immunocompromised
Valacyclovir (variant) - better oral availability
Famciclovir - DOC herpes zoster
Resistance and toxicity of acyclovir
No toxicity
Resistance via mutated viral thymidine kinase
Mech of gancyclovir
5’-mono phosphate formed by CMV viral kinase
Guanosine analog
Triphosphate formed by cellular kinases
Preferentially inhibits viral DNA polymerase
Clinical use of gancyclovir
CMV (esp immunocompromised )
Prodrug (valgancyclovir) has better oral availability
Toxicity of gancyclovir
Leukopenia, neutropenia, thrombocytopenia, & renal toxicity
More toxic than acyclovir
Mech of resistance in gancyclovir
Mutated CMV DNA polymerase or lack of viral kinase
Mech of foscarnet
Viral DNA polymerase inhibitor that binds to pyrophosphate binding site of the enzyme
Does not require activation by viral kinase
*FOScarnet = pyroFOSphate analog
Clinical use of foscarnet
CMV retinitis (immunocompromised) if gancyclovir fails Acyclovir-resistant HSV
Foscarnet toxicity
Nephrotoxicity
Foscarnet mech of resistance
Mutated DNA polymerase
Mech of Cidofovir
Preferentially inhibits viral DNA polymerase
Does not require phosphorylation by viral kinase
Clinical use of Cidofovir
CMV retinitis (immunocompromised)
Acyclovir - Resistant HSV
Long half life
Toxicity of Cidofovir
Nephrotoxicity
* coadminister with probenecid and IV saline to reduce toxicity
Mech of interferons
Glycoproteins synthesized by virus-infected cells
Block replication of both RNA and DNA viruses
Clinical use of interferons
variable dependent on type (alpha, beta, gamma)
Toxicity of interferons
Neutropenia
Myopathy
INF-alpha treatment
Hep B & C
Kaposi’s Sarcoma
HPV
INF- beta treatment
MS
