Antiviral Drug List

Question 1

What are the viruses targeted by Acyclovir?

Answer 1

Herpes Simplex Virus and VZV (varicella-zoster)

Question 2

What is the mechanism of action of Acyclovir?

Answer 2

structural analog of deoxyguanosine
phosphorylated by viral thymidine kinase (TK)
preferential incorporation by viral DNA polymerase
causes chain termination

Question 3

What is the bioavailability of Acyclovir?

Answer 3

~20% oral bioavailability (valacyclovir is 3-5X better (taken up by transporters in intestine + kidney)
penetrates CSF

Question 4

What is the toxicity of Acyclovir?

Answer 4

generally well-tolerated

Question 5

What is the type of resistance to Acyclovir?

Answer 5

mutations in TK or viral polymerase

Question 6

What is the mechanism of action of Foscarnet?

Answer 6

binds to pyrophosphate site of viral polymerase (also RTase)

100-fold greater selective inhibitor of viral versus human polymerase

Question 7

What is the virus targeted by Foscarnet?

Answer 7

HSV or CMV (especially if it is resistant to Acyclovir)

Question 8

What is the bioavailability of Foscarnet?

Answer 8

IV administration

penetrates CNS

Question 9

What is the type of resistance to Foscarnet?

Answer 9

mutations in polymerases

Question 10

What is the toxicity of Foscarnet?

Answer 10

nephrotoxicity is high (~30%) but reversible

hypocalcemia and CNS toxicity is also significant (25% pts)