Anti Viral Agents Flashcards
Antivirals that work through host cell kinases.
AZT(Zidovudine) and nucleoside analogues – phosphorylated by cell kinases. Turns to nucleotides that
Antivirals that work through viral kinases.
Acyclovir (Thymidine Kinase) and Gancyclovir (CMV protein kinase, UL97) – first phosphorylated by viral kinases.
Why is Acyclovir more selectively toxic than other antivirals?
because it is phosphorylated by Thymidine kinase a viral kinase.
Three viruses that Acyclovir can be used against.
Herpes simplex, Epstein Barr, and VZV
Two indications for Valacyclovir.
L-valine ester prodrug of acyclovir. Recurrent genital herpes, zoster infections (shingles).
Three indications for Famciclovir.
Oral prodrug of Penciclovir. Acute Herpes Zoster, suppression of recurrent genital herpes.
Early symptoms and DOC for Herpes Encephalitis.
Acute onset of fever, headache, decreased consciousness and seizures. Acyclovir
How Ganciclovir is metabolized to an active form inside the host cells.
Guanosine analogue – phosphorylated first by virus then 2nd and 3rd by Host cell. Forms Nucleotide that inhibits CMV.
How Cidofovir has selective toxicity.
Cytosine analog. 1000X more effective against viral DNA-polymerase than host DNA polymerase. Reno toxic – coadministered with Probenecid.
What is unique about the metabolism requirement for Foscarnet?
Inhibits viral DNA-polymerase, RNA-polymerase, and HIV-RT directly – no activation by phosphorylation required.
Four viruses treatable by Foscarnet?
Herpetics, Hep B, and HIV
Viral replication
Attachment. Entry through membrane. Uncoating of Genetic material. Synthesis of early regulatory proteins. Synthesis of RNA/DNA. Synthesis of late structural proteins. Assembly/maturation of viral particles. Release from host.
CDC guideline Tx for influenza in Adults.
Rimantadine for adults only. Zanamivir is apropriate if older than 7.
MOA of neuraminidase inhibitors.
Inhibit viral cleavage of sialic acid – inhibits the release of newly formed viruses. (Zanamivir and Oseltamivir)
Site of action for Palivizumab
Binds to fusion protein of RSV. Prevents infection of host cell – reduce replication and spread.
Dosing and timing of Paluvizumab for RSV(Respiratory Syncytial Virus)
15mg/Kg given IM monthly x up to 5 doses during RSV season.
Who should avoid contact with patients using Ribavirin? Why?
Those at risk of becoming pregnant. Inhaled teratogenic.
Why is selective toxicity more difficult with viruses than with bacteria?
fewer differences between viral and host machinery to exploit – viruses tend to use the host mechanics. Also broad variety of heterogenous agents.
Difficulties in developing drugs against viruses.
heterogenous nature of viruses makes it hard to come up with a broad treatment antiviral.
Three indications for Acyclovir
Mucocutaneous herpetic lesions, genital herpes lesions, and prophylaxis in AIDS and other immunocompromised patients.
Two blood related adverse effects of ganciclovir.
Leukopenia and Thrombocytopenia
What could be monitored to determine the duration of Foscarnet action?
Kidney clearance is directly proportionate to creatinine clearance.
Major toxicity of Zanamavir and contraindications.
Bronchospasm. Not for pts with underlying airway disease (COPD, Asthma)