Anti-Virals

Question 1

Antivirals for HSV and/or VSV

Answer 1

1. acyclovir
   - primarily prescribed for HSV; less active against VZV
2. Valacyclovir
   - converted to acyclovir, higher serum levels
3. Penicyclovir
   - topical only due to poor oral absorption
4. Famcylovir
   - metabolized to pencyclovir
   - oral use only
   - mainly used for VZV
   Efficacy for VZV: famiciclovir >

Valcyclovir&raquo_space;>acyclovir

Patient must hydrate to avoid crystalline nephropathy

Question 2

Antiviral for HSV or CMV

Answer 2

1. Gancylovir
   - for prophy or treatment of CMV
   - contraindicated during pregnancy, males who wish to reproduce
2. foscarnet
   - Inhibits viral DNA polymerase enzyme
   - Nephrotoxicity
   - safer than gancylovir
   - useful in acyclovir or gancyclovir resistant HSV/CMV

Question 3

Antivirals for Flu

Answer 3

1. Oseltamivir
   - active against both flu A and B
   - early administration is crucial
   - when a 5 day course of treatment is initiated within 48 hrs from onset of flu-symptoms, the duration of flu symptoms are decrease up to 1-2 days
   - disulfiram like reaction
2. Zanamivir
   - for the treatment and prophy of flu A and B
   - available as inhaler only
   - disulfiram like reaction
   - contraindicated in patients with severe, asthma, COPD, and allergies to milk proteins
3. Amantadine
   - Only active against flu A
   - adverse effects: ataxia, dizziness, anxiety, slurred speech.
   - an anti-parkinson’s drug historically