7. Antiviral drug
Targeting viral function Targeting cellular function that virus needs
Nucleic acid polymerases proteases Integrases Neuraminidases
DNA dependent
DNA polymerase
RNA dependent
RNA polymerase
DNA dependent
RNA polymerase
8.
9. Acyclovir
• Acyclovir (acycloguanosine) represent a new generation of antiviral agents,
mainly because of the unique mechanism of action. This purine nucleoside is
phosphorylated more efficiently by virus-induced thymidine kinase than host
thymidine kinase. Once activated to the triphosphate form, it is a better
substrate and inhibitor of viral, versus host, DNA polymerase.
• Acyclovir is relatively safe (probenecid renders the drug safer) and is useful
against a variety of infections caused by DNA viruses, especially the
herpesvirus family.
10. Valacyclovir
• Valacyclovir, L-valyl ester from acyclovir, is also available in oral form. After
swallowing, drug is immediately changed to acyclovir by the substance
valacyclovir hydrolase in the digestive tract and liver.
11. Penciclovir & Famciclovir
• Penciclovir is basically like ganciclovir, in contrast only by replacing the
methylene connection for oxygen either in the non-cyclic ribose portion of the
particle. Its digestive component and activity are similar to acyclovir, so
again, it is only a DNA chain terminator that is bound.
• Famciclovir is a simple diacetyl-6-deoxy from penciclovir. All this is
assimilated after oral organization and is quickly used for penciclovir by
deacetylation in digestive tract, blood and liver, next it is oxidized by liver in
position 6 of purine cycle.
12. Ribavirin
• Ribavirin is a synthetic triazole nucleoside (an analogue of guanosine) with a
broad spectrum of activity against many RNA and DNA viruses, both in vitro
and in vivo. Susceptible viruses include adenoviruses, herpesviruses,
orthomyxoviruses, paramyxoviruses, poxviruses, picornaviruses,
rhabdoviruses, rotaviruses, and retroviruses.
13. Zidovudine
• Zidovudine (azidothymidine, AZT) is a thymidine analogue. Within the virus-
infected cell, the 3′-azido group is used by retroviral reverse transcriptase and
incorporated into DNA transcription, preventing viral replication.
• The drugs tend to be effective for acute infections but are relatively
ineffective for chronically infected cells.
14. Interferon
• Interferons are low molecular weight glycoprotein cytokines produced by host
cells in response to the viral infections.
• Their receptors are JAK-STAT tyrosine protein kinase receptors which on
activation phosphorylate cellular protein, which migrate to the nucleus and
induce transcription of interferon- induced- proteins which exert antiviral
effect.
