anti-viral drugs

1. ANTI-VIRAL DRUGS
Yogapriya.v
B.Opt(IIIyr)

2. INTRODUCTION
• Viruses are intracellular parasites
• They depend on the host cell for food,growth and multiplication
• There are two types of viruses=DNAviruses and RNAviruses
• Retrovirus is a type of RNA virus which causes AIDS

3. CLASSIFICATION OF ANTIVIRAL DRUGS
ANTI-HERPES VIRUS AGENT • Acyclovir
• Gancyclovir
• famcyclovir
ANTI-INFLUENZA VIRUS AGENT • Amantadine
• Rimantadine
ANTI-RETROVIRAL AGENTS
i)Nucleoside reverse transcriptase
inhibitors(NRTI)
• Zidovudin
• Didanosine
• Zalcitabine
ii)Non-nucleoside reverse
transcriptase inhibitors(NNRTI)
• Nevirapine
• Efavirenz
• Delavirdine

4. ACYCLOVIR
• Acyclovir is a purine analogue
• The drug is more specific in affecting viral particle
• As it is activated only by virus induced thymidine kinase and converted to an
acyclomonophosphate form and then to a triphosohate form
• Inhibits virus induced DNA polymerase
Advantage
• Penetrates intact corneal epithelium and achieves sufficient viricidal concentration in
aqueos
• More selective therefore it is less toxic
• More active than other agent
• Wider spectrum than other agents
• Can cross blood brain barrier and probably blood ocular barrier

5. Preparations
• 3% ophthalmic ointment
• 200 mg capsules
• 5% dermal cream
Dose for ocular lesion
• For primary HSV blepharitis and orofacial lesions, 5% dermal cream 5
times/day is effective
• For HSV superficial and deep corneal lesions 3% ointment 5 times/day till
the lesionsheal,then reduced to 2 to 3 times/day
• Maximum period of therapy is 14 days
• For HSV iritis apart from topical ointment,oral acyclovir 400 mg 5
times/day for 10 days withsteroids can be given

6. ADENINE ARABINOSIDE
• Adenine arabinoside is apurine analogue
• Once phosphorylated by viral thymidine kinase,Ara-A becomes
triphosphorylated
• In this form it inhibits DNA polymerase and ribonucleotide reductase,blocking
the DNA synthesis
• Thus its action is different from IDU and trifluridine
• It doesnot incorporate into viral DNA
• Unlike IDU.Ara-A can achieve better viricidal concentration in the aqueous
humour
• It can be used in stromal viral keratitis and iritis
• It can cross blood ocular barrier too
Preparations
Available in 3% ointment

7. Dosage
• 5 times/day
• If there is no improvement,the drug should be discontinued in 7 days
Adverse reaction
• External ocular reactions are just similar to IDU
• Allergic reaction

8. TRIFLURIDINE
• Trifluridine or triflurothymidine is again a pyrimidine analogue
• It is halogenated pyrimidine in which three fluorines,instead of iodine,occur at
5 methyl group of thymidine
• So the mechanism and spectrum is almost equal to IDU
Advantages
• It is 10 times more soluble than IDU.therefore it penetrate well
• More specific with viral DNA,therefore it is less toxic
• Effective against IDU resistant organisms

9. Adverse effect
• Mild burning sensation is common after topical instillation
• Other reactions like superficial puctate keratitis,hypersensitivity reaction and
hyperemia can occur
• Severe bone marrow depression in systemic administration has been reported
Preparation
1% solution is available
Dose
• 1 drop every 1hr/day time,every 2hr/night time is advisable
• After the epithelium is formed the dose is reduced to 4 times/day for 7 days
• If the healing is not complete in 14 days,the drug should be discontinued

10. IDOXYURIDINE
• Idoxyuridine is a halogenated pyrimidine where 5 methyl group of thymidine is
replaced by iodine
• It is otherwise called 5 iodo 2 deoxy uridine
• Viral DNA synthesis becomes defective due to the incorporation of IDU into DNA
Ophthalmic uses
• It is topically used against herpes simplex and vaccinia keratitis
• It is poorlu soluble in water and doesnot penetrate the stroma
• Therefore it is not useful in deeper infections

11. Preparations
• 0.1% ophthalmic ointment
• 0.5% ointment
• Unstable in heat and light and refrigeration is advisable
• Old solution should be discarded
Dose
• During first week one drop is instilled in the eye every hour during day and every
2 hours at night
• If ointments is used it can be applied 4 times a day
• If there is no response in 5 to 7 days,change to another antiviral agent is
necessary to counteract presumed resistance

12. THANK YOU FOR
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