Antiviral Drugs

Question 1

Classification

Answer 1

1. Herpes infection- Acyclovir, valacyclovir, famiclovir, foscarnet, idoxuridine
2. Retroviral infections-
   a. NRTI - Zidovudine, lamivudine, abacavir, zalcitabine, tenofovir.
   b. NNRTI- Nevirapine, Delavirdine, Efavirenz.
   c. Protease inhibitor- Saquinavir, Ritika it, lopinavir, nelfinavir, amprenavir.
   d. Fusion inhibitor- Enfuviritide, Maraviroc.
   e. Integrase inhibitor- Raltegravir.
3. Anti influenzas- Amantidine, Rimantadine, Oseltamivir, zanamivir.
4. Other antiviral agents- Interferons, Ribavirin.

Question 2

Acyclovir

Answer 2

MOA- inhibits viral DNA synthesis and replication. It is activated to triphospate derivative which inhibits virus DNA polymerase competatively, gets incorporated and stops lengthening of DNA strand.

Has high therapeutic index and low toxicity to host.

Uses: 1. Genital herpes simplex

2. Mucocutaneous herpes simplex
3. H. Simplex Encephalitis
4. H. Simplex type 1 keratitis
5. Herpes zoster
6. Herpes whitlow
7. Chicken pox

Question 3

Zidovudine

Answer 3

Effective against HIV1 and HIV2
Crosses BBB and placental barrier, secreted in milk.
Also used for post exposure prophylaxis and to prevent vertical transmission.

MOA: Enters HIV infected cells, and converted to triphosphate forms by cellular kinases and competatively inhibits HIV’s reverse transcriptase.
Gets incorporated into growing viral DNA and cause termination of chain elongation of proviral DNA.

Drug interactions:
Zidovudine + paracetamol- paracetamol competes and interferes with glucuronide conjugation of zidovudine.

Zidovudine + azoles - inhibits metabolism of zidovudine

Zidovudine + stavudine - competes for intracellular phosphorylation

Question 4

Treatment of HIV infection

Answer 4

Principle: combination of 2NRTIs+ NNRTI/PI

First line ART Regimen :
Tenofovir+ 3 Emtricitabine + Efavirenz

Post exposure prophylaxis: