SF - anti-virals Flashcards
What is the therapeutic index for anti-virals?
Low
What is the most effective preventative step of anti-virals?
Preventing viral attachment. This would be via immunisation of viral proteins. Interferon targets can also be useful.
What are the functions and mechanisms of amantadine?
To prevent viral attachment.
Inhibits penetration and uncoating of influenza A virus in humans. So used prophylactically.
Analgesic action via inhibiting NMDA glutamate receptors.
What is the mechanism of idoxuridine?
Iodine is added to the base.
Incorporated into viral DNA.
Presence of iodine prevents base pairing.
Inhibits DNA replication, particularly for herpes virus A.
How is idoxuridine administered, and why?
Topically. This is because it inhibits mammalian DNA synthesis, so cannot be given systemically.
What is idoxuridine used to treat?
Herpetic keratitis
What type of drug is aciclovir?
Prodrug. Needs to be phosphorylated before it is activated.
How is aciclovir activated?
Phosphorylated by viral thymidine kinase, and then it is phosphorylated by host kinases.
What is the function of aciclovir?
DNA polymerase inhibitor -> prevents nucleotide assembly.
What is aciclovir administered for? How is it administered?
Herpes infection.
Administered by ophthalmic ointment, skin ointment, tablet or injection.
What are the mechanisms of resistance to aciclovirs?
Mutations of viral thymidine kinases.
Mutations of DNA polymerase.
What is the function of azidothymidines (AZT)?
Reverse transcriptase inhibitor.
DNA polymerase inhibitor at a higher dose.
What type of drug is AZT?
Prodrug - needs to be phosphorylated to be activated.
What is AZT used to treat? What are some of the side effects?
FIV-positive cats. Increases survival time and quality of life.
Hepatotoxicity and anaemia.
Contraindicated in cats with renal or hepatic impairment.
What is the function of vidarabine? What class of anti-virals is it from?
Aciclovir.
Analogue of adenosine.
DNA polymerase inhibitor.
Inhibits viral and host cell enzymes.
