Antiviral & Retroviral

Question 1

Classify antiviral drugs based on the diseases used for

Answer 1

Anti herpes: Acyclovir, Valacyclovir
Anti influenza: Oseltamivir, Amantadine, rimantadine
Anti hepatitis B: Lamivudine, Tenofovir
Anti hepatitis C: Interferon Alpha

Question 2

MOA of acyclovir

Answer 2

Acyclovir converted to active metabolite acyclovir monophosphate by a virus specific enzyme called herpes virus specific thymidine kinase. It is then converted to acyclovir triphosphate by cellular kinases which competitively inhibit viral DNA pol and Integrate to the viral DNA which terminates lengthening of the DNA which will irreversibly inhibit DNA Pol

Question 3

Why does acyclovir not have human toxicity

Answer 3

Because it needs a virus specific enzyme and has low affinity for human DNA

Question 4

Acyclovir is active against:-

Answer 4

HSV1 > HSV2 > VZV=EBV

Question 5

Resistance to acyclovir

Answer 5

VZV and EBV
VZV: mutation which causes deficient enzyme production
EBV: enzyme loses affinity for acyclovir

Question 6

Uses of acyclovir

Answer 6

1. Genital herpes simplex
2. Mucocutaneous Herpes simplex
3. H. simplex encephalitis
4. H. Simplex keratitis
5. Herpes Zoster
6. Chicken pox

Question 7

Most prominent ADR of acyclovir

Answer 7

Dose dependent decrease in GFR

Question 8

Adverse drug effects of acyclovir

Answer 8

Topical: stinging and burning sensation
Oral: nausea, vomiting, headache, CNS effects
IV: Rashes, urticaria, nausea vomiting, fall in bp

Dose dependent reduction in gFr most important toxicity
Reversible neurological manifestations include tremors, lethargy, disorientation, hallucinations, convulsion, coma

Question 9

Drug for CMV

Answer 9

Ganciclovir