DNA Antivirals

Question 1

What is the general common mechanism for “-ovirs” and NRTI’s?

Answer 1

inactive prodrugs that require activation by host enzymes to bind to the nucleic acid polymerase and cause chain termination

Question 2

What is acyclovir active against?

Answer 2

herpes simplex virus
varicella zoster virus

• only works with actively replicating viruses, so can reduce symptoms but will never wipe out latency

Question 3

What is the use of ganciclovir?

Answer 3

CMV infections, including retinitis and in immunosuppressed patients
- due to viral specific enzyme inhibition

Question 4

What are the side effects of acyclovir?

Answer 4

• low toxicity! No bone marrow suppression

- adverse CNS effects when dosed too high in the presence of renal insufficiency

Question 5

What are the side effects of ganciclovir?

Answer 5

Bone marrow suppression (leukopenia, thrombocytopenia)

• mucositis, fever, rash, crystalluria
• adverse CNS effects in high doses

Question 6

What is the mechanism and use of foscarnet?

Answer 6

• inhibits viral DNA and RNA polymerases
• useful for HSV, VZV, CMV, especially in the setting of acyclovir resistance
• dose dependent renal and CNS toxicity