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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.
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Antiviral Drugs
Harindu Udapitiya.Temporary Lecturer,Division Of Pharmacology,Department of Oral Medicine & Periodontology.
Overview
• 1.Introduction to virus and replication.• 2.Targets of Antivirals.• 3.Antiviral Drugs.
– Mode of Action– Pharmacokinetics– Clinical Use– Adverse effects
1.Introduction to virus and replication.
Structure of a virus
Viral Replication
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.
Antiviral Drugs
• 1.Inhibition of penetration & attachment to host cells.
I. Amantidine
II. Immunoglobulin
2.DNA polymarase inhibitors.III. Aciclovir
IV. Ganciclovir
V. Tribavirin
• 3.Reverse Transcriptase inhibitorsI. Zidovudine
II. Lamivudine
• 4.Protease inhibitorsI. Saquinavir
II. Ritonavir
• 5.Inhibitors of virus release.I. Oseltamivir
II. Zanamivir
• 6.Interferones(INF)
• 1.Inhibition of penetration & attachment to host cells
Amantidine
• Mode of actionBlocks M2 receptors
• PharmacokineticsWell absorbed orallyT1/2=3hElimination-renally
• Adverse Effects Anxiety Insomnia Hallucination
Immunoglobulin
• 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
• 2.DNA polymarase inhibitors.
Aciclovir
•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
• Adverse EffectsReversible nephropathyHeadache,nauseaEncephalopathy
• Clinical Use Varicella zoster-shingells,chikenpox Herpes zoster Prophylactically for immunocompramised patients.
Gangcyclovir
• MOASame as aciclovir
• Pharmacokinetics IV,oral T1/2=4h Elimination-renal
• Adverse Effects Bone marrow suppresion Potential carcinogenicity
• Clinical Use– CMV infection
3.Reverse Transcriptase inhibitors
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.
4.Protease inhibitors
Saquinavir
• Uses with combination of ritonavir.• Oral• Protein binding 98%• T1/2=9-15 h• Use in HIV therapy.
5.Inhibitors of virus release.
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
Zanamivir
• Oral,inhalation• Oral BA=2%• T1/2=2.5-5h• Elimination-renal• Use in infl A & B• Adverse effects
– Broncospasms– Cough
Interferones
• 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.
• Iv,Im• T1/2=2-4h• Clinical use
Hepatitis B & C
• Adverse effecctsFeverMyelgiaBM suppression Rashes
Summery• 1.Introduction to virus and replication.• 2.Targets of Antivirals.• 3.Antiviral Drugs
– Amantidine– Immunoglobulin– Aciclovir– Gangcyclovir– Zidovudine– Saqunavir– Oseltamivir– Zanamivir
• Interferones
Furthur reading…
1. Viral vaccines
2. DNA & RNA Viruses
3. HIV treatment.