Antivirals

Question 1

What are 4 goals of antiviral treatment?

Answer 1

1. Prevent viral entry
2. Prevent replication
3. Inhibit viral uncoating
4. Inhibit viral processing

Question 2

What does HSV suppressive therapy do?

Answer 2

Reduces frequency and severity of recurrence but NOT viral shedding; Decreases risk of transmission

Question 3

Which drugs treat Herpes viruses?

Answer 3

Acyclovir and Valacyclovir

Question 4

What is the MOA of Acyclovir?

Answer 4

Taken up by all host cells but requires 3 phoshphorylation steps to be activated. Becomes monophosphate by viral thymidine kinase. Becomes triphosphate by host cell enzymes; Inhibits viral DNA polymerase by competing with GTP causing chain termination.

Question 5

What are the pharmacokinetics of Acyclovir?

Answer 5

1. Poor oral bioavailability

2. Good penetration into bodily fluids

Question 6

What is the resistance to Acyclovir?

Answer 6

1. Absence or partial production of viral thymidine kinase.

2. Altered thymidine kinase specificity.

Question 7

Describe valacyclovir

Answer 7

A pro-drug of acyclovir with better oral bioavailability, similar side effects and improved effectiveness against VZV. Similar efficacy in treating HSV

Question 8

What are the side effects of acyclovir?

Answer 8

Topical: rash
Oral: NVD
IV: Renal insufficiency and neurotoxicity.