anti viral drugs classification structure activity relationship SAR Acyclovir vs penciclovir ganciclovir vidarabin medicinal chemistry pharmacy M.pharm mechanism of action

1. ANTIVIRAL AGENTS
Farman Ahmad
Department of pharmaceutical sciences & natural products (cupb)

2. CONTENT
•Introduction
•Classification
•Structure Activity Relationship (SAR)

3. Introduction
Anti-viral- Anti=against, Viral=Infection caused by Virus
Antiviral agents are the drugs which are developed to effectively treat an
infection caused by a virus
Virus is a submicroscopic infectious agent (pathogen) that replicates only
inside living cells
Typically a virus consist a segment of nucleic acid(DNA or RNA) surrounded by
a protein coat
Virus can infect all forms of life from animal and plants to microorganisms

4. CLASSIFICATION
Based on Virus:-
Non-
Retrovirus
Anti-
Hepatitis
Hepatitis B
Lamivudin
Adefovir
dipivoxil
Tenofovir
Hepatitis C
Ribavirin
Interferon alpha
Anti-
Influenza
Amantadine
Rimantadine
Oseltamivir
Zanamivir
Anti-
Herpes
Idoxuridine
Trifluridine
Acyclovir
Valacyclovir
Famciclovir
Ganciclovir
Valganciclovir
Cidofovir
Foscarnet
Fomivirsen

5. CLASSIFICATION
Based on Virus:-
Retrovirus
Nucleoside
reverse
transcriptas
e inhibitors
Zidovudine
Didanosine
Stavudine
Lamivudine
Abacavir
Emtricitabine
Tenofovir
Non-
nucleoside
reverse
transcriptas
e inhibitors
Nevirapine
Efavirenz
Delavirdine
Protease
inhibitors
Ritonavir
Atazanavir
Indinavir
Nelfinavir
Saquinavir
Amprenavir
Lopinavir
Entry
inhibitor
Enfuvirtide
CCR-5
receptor
inhibitor
Maraviroc
Integrase
Inhibitor
Raltegravir

7. CLASSIFICATION
Based on Chemical Nature:-
Admantane Derivatives:-
Amantadine, Rimantadine, Somantadine, Tromantadine.
Purine Analogue:-
Acyclovir, Ganciclovir, Vidarabine, Valaciclovir, Penciclovir
Pyrimidine Analogue:-
Trifluridine, Idoxuridine, Zidovudine, Stavudine, Emtricitabine
Phosphorus Derivatives:-
Foscarnet, Tenofovir
Thiazolides:-
Nitazoxanide

8. Chemical Structures

9. Mechanism of action:-
1. Purine Analogue

10. Mechanism of action:-
2. Admantane derivatives
Inhibit viral replication by blocking the proton channel formed by the M2 protein
of influenza A virus.
The channel activity is necessary for viral particle un-coating during early and late
stages of viral replication.

11. Mechanism of action:-
3. Pyrimidine analogue:-
Iodinated thymidine analog, activated intra-cellularly to tri-phosphate which
can inhibit DNA polymerases required for incorporation of thymidine into viral
DNA.
Idoxuridine, instead of thymidine, is incorporated into viral DNA, resulting in
faulty DNA and the inability of the virus to infect tissue or reproduce.

12. Structure Activity Relationship(SAR)
Acyclovir:-
Acyclic side chain at N-9 is essential for
anti-viral activity
Removal of –CH2OH group from side
chain, inactive analogue obtained
The 9-alkoxy derivative is highly active
against Simplex and Vericella zoster
virus, obtained by slight modification at
acyl side chain

13. Acyclovir V/S Ganciclovir
 Ganciclovir differ from acyclovir by a single carboxyl side chain
 Ganciclovir 50 times more potent than acyclovir against
CMV(Cytomegalovirus) due to absence of thymidine kinase in CMV.
 Ganciclovir not require phosphorylation for producing its action against
CMV.

14. Acyclovir V/S Vidarabin
 The use of vidarabine was replaced by acyclovir because of poor solubility
and toxicity for herpes simplex virus infection.
 The mortality rate was found to be 19% for acyclovir and 50% for vidarabin

15. Acyclovir V/S Penciclovir
 Penciclovir has a higher affinity for HSV TK than acyclovir
 the levels of penciclovir triphosphate in infected cells are much higher
than the levels of acyclovir triphosphate

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