This presentation gives a basic pharmacological knowledge about commonly using antivirals.This contains basic mechanism of viral action and mode of action,indication, adverse effects about each of antivirals.

1. Antiviral Drugs
Harindu Udapitiya.
Temporary Lecturer,
Division Of Pharmacology,
Department of Oral Medicine & Periodontology.

4. Overview
• 1.Introduction to virus and replication.
• 2.Targets of Antivirals.
• 3.Antiviral Drugs.
– Mode of Action
– Pharmacokinetics
– Clinical Use
– Adverse effects

5. 1.Introduction to virus and replication.

6. Structure of a virus

7. Viral
Replication

9. Targets of Antiviral Drugs
• 1.Inhibition of penetration & attachment
to host cells.
• 2.DNA polymarase inhibitors
• 3.Reverse Transcriptase inhibitors
• 4.Protease inhibitors
• 5.Inhibitors of virus release.

10. Antiviral Drugs
• 1.Inhibition of penetration & attachment
to host cells.
I. Amantidine
II. Immunoglobulin
2.DNA polymarase inhibitors.
I. Aciclovir
II. Ganciclovir
III. Tribavirin

11. • 3.Reverse Transcriptase inhibitors
I. Zidovudine
II. Lamivudine
• 4.Protease inhibitors
I. Saquinavir
II. Ritonavir
• 5.Inhibitors of virus release.
I. Oseltamivir
II. Zanamivir

12. • 6.Interferones(INF)

13. • 1.Inhibition of penetration &
attachment to host cells

14. Amantidine

15. • Mode of action
 Blocks M2 receptors
• Pharmacokinetics
 Well absorbed orally
 T1/2=3h
 Elimination-renally
• Adverse Effects
 Anxiety
 Insomnia
 Hallucination

16. Immunoglobulin

17. • Contains antibodies which are directed
against the virus envelope and can
'neutralise' some viruses and prevent
their attachment to host cells.
• Use in,
– Measles
– infectious hepatitis
– German measles
– Rabies
– poliomyelitis

18. • 2.DNA polymarase
inhibitors.

19. Aciclovir

20. • Mechanism of action
Aciclovir viral thiamidine kinase Aciclovir monophosphate
DNA polymarase Aciclovir triphosphate
• Pharmacokinetics
 Oral,IV,Topical
 oral BA 10-20%
 Plasma T1/2-2-3h
 Distribute 50% to CSF
 Elimination-Renal

21. • Adverse Effects
Reversible nephropathy
Headache,nausea
Encephalopathy
• Clinical Use
 Varicella zoster-shingells,chikenpox
 Herpes zoster
 Prophylactically for immunocompramised patients.

22. Gangcyclovir
• MOA
Same as aciclovir
• Pharmacokinetics
 IV,oral
 T1/2=4h
 Elimination-renal
• Adverse Effects
 Bone marrow suppresion
 Potential carcinogenicity

23. • Clinical Use
– CMV infection

24. 3.Reverse Transcriptase
inhibitors

25. Zidovudine
• Necleoside analog
• Oral,iv,rectal
• Oral BA=75%
• T1/2=05-3h
• Elimination=renal
• Use in treatement for HIV infection & as
post exposure prophylactic.

26. 4.Protease inhibitors

27. Saquinavir
• Uses with combination of ritonavir.
• Oral
• Protein binding 98%
• T1/2=9-15 h
• Use in HIV therapy.

28. 5.Inhibitors of virus release.

29. Oseltamivir
• Oral BA=75%
• Oseltamivr hepatic estarase oseltamivir
carboxylase
• Widely distributed through body
• T1/2=6-10h
• Elimination=renal
• Use in Influenza A,B
• Adverse effects
– Nausea,vomiting,abdominal pain

30. Zanamivir
• Oral,inhalation
• Oral BA=2%
• T1/2=2.5-5h
• Elimination-renal
• Use in infl A & B
• Adverse effects
– Broncospasms
– Cough

31. Interferones

32. • Interferons are a family of inducible
proteins synthesised by mammalian cells
• They induce, in host cell ribosomes, the
production of enzymes that inhibit the
translation of viral mRNA into viral
proteins, thus halting viral replication.
• Wide sprectum of use.

33. • Iv,Im
• T1/2=2-4h
• Clinical use
Hepatitis B & C
• Adverse effeccts
Fever
Myelgia
BM suppression
Rashes

34. Summery
• 1.Introduction to virus and replication.
• 2.Targets of Antivirals.
• 3.Antiviral Drugs
– Amantidine
– Immunoglobulin
– Aciclovir
– Gangcyclovir
– Zidovudine
– Saqunavir
– Oseltamivir
– Zanamivir

35. • Interferones

37. Furthur reading…
1. Viral vaccines
2. DNA & RNA Viruses
3. HIV treatment.