فايرل

• Antiviral drugs


  A class of medication used specifically for treating viral infections. Unlike most antibiotics, antiviral drugs do not destroy their target pathogen; instead they inhibit their development.

  
• Viruses

  • Obligate intracellular parasite, lack cell wall, cell membrane and metabolic process, so it depends on host metabolic process
• Virus life cycle


  1. Attachment to a host cell

  2. Release of viral genes and possibly enzymes into the host cell

  3. Replication of viral components using host-cell machinery

  4. Assembly of viral components into complete viral particles

  5. Release of viral particles to infect new host cells

  
• Anti-receptor antibodies


  Can inhibit the attachment of viruses to host cells
• Anti-VAP antibodies, receptor anti-idiotypic antibodies


  Can inhibit the attachment of viruses to host cells

  
• Entry inhibitor


  Drugs that inhibit the entry of viruses into host cells

  
• Uncoating inhibitor


  Drugs that inhibit the uncoating of viruses within host cells

  
• Reverse transcription inhibitors


  Drugs that inhibit the reverse transcription of viral RNA into DNA

  
• Integrase inhibitors


  Drugs that inhibit the integration of viral DNA into the host cell genome

  
• Transcription inhibitors


  Drugs that block the attachment of transcription factors to viral DNA
• Translation/antisense inhibitors


  Drugs that use "antisense" molecules to target critical sections of viral genomes
• Protein processing inhibitors


  Drugs that interfere with post-translational modifications or targeting of viral proteins
• Protease inhibitors


  Drugs that inhibit viral proteases that cut viral protein chains apart
• Assembly inhibitors

  Drugs that inhibit the assembly of viral components into complete viral particles
• Release inhibitors


  Drugs that prevent the release of completed viruses from host cells

  
• Immune system stimulation


  Tactics that encourage the body's immune system to attack viruses, rather than attacking them directly
• Neuraminidase inhibitor

  Drugs that prevent the release of viral particles by blocking neuraminidase, a molecule found on the surface of flu viruses

  
• Oseltamivir


  A neuraminidase inhibitor that prevents the release of influenza A and B viruses from infected cells

  
• Amantadine and rimantadine


  Drugs that block the viral membrane matrix protein which acts as an ion channel, needed for fusion of viral protein with cell membrane to form endosome, and also block the release of new virus

  
• Ribavirin


  A synthetic guanosine analogue that blocks GTP formation and RNA polymerase, used to treat influenza, RSV, and chronic hepatitis C

  
• Acyclovir

  A guanosine analogue that is monophosphorylated by viral thymidine kinase, then converted to di- and triphosphate forms that inhibit viral DNA polymerase and cause premature viral DNA chain termination

  
• Cidofovir


  A nucleotide analogue that inhibits viral DNA synthesis, used for cytomegalovirus retinitis

  
• Fomivirsen


  A drug that blocks cytomegalovirus mRNA, used for CMV iritis and vitritis
• Foscarnet


  A pyrophosphate derivative that blocks viral DNA and RNA polymerases, used for CMV retinitis, acyclovir-resistant herpes simplex, and herpes zoster
• Ganciclovir


  An acyclovir analogue that blocks DNA polymerase, used only for cytomegalovirus
• Vidarabine


  A nucleoside analogue that is converted to a triphosphate form that inhibits viral DNA polymerase, used for herpes simplex, herpes zoster, and CMV

  
• Reverse transcriptase inhibitor (RTI)


  Drugs that inhibit the reverse transcriptase enzyme of HIV, classified into nucleoside (NRTI) and non-nucleoside (NNRTI) types

  
• Protease inhibitor


  Drugs that inhibit the protease enzyme of HIV
• Viral fusion inhibitor (Enfuviritide)


  A drug that inhibits the viral transmembrane glycoprotein (GP41) responsible for viral binding to host cells
• Zidovudine


  A NRTI that is converted to a triphosphate form that inhibits HIV reverse transcriptase

  
• Zalcitabine


  A NRTI that inhibits reverse transcriptase and DNA polymerase, causing peripheral neuropathy and pancreatitis

  
• Lamivudine


  A NRTI that blocks reverse transcriptase and DNA synthesis with less mitochondrial toxicity than other NRTIs

  
• Nevirapine


  A NNRTI that is a highly selective, non-competitive inhibitor of HIV reverse transcriptase

  
• Delavirdine


  A NNRTI that is well absorbed and not affected by food

  
• Zalcitabine


  It inhibits RTE and DNA polymerase

  
• Zalcitabine


  • Absorbed orally but affected by food
  • It causes peripheral neuropathy due to inhibition of host mitochondrial DNA polymerase
  • Pancreatitis

  
• Lamivudine

  Blocks RTE and DNA synthesis, it causes less side effects because it does not block host mitochondrial DNA

  
• NNRTI (non-nucleoside reverse transcriptase inhibitor)


  Highly selective non-competitive inhibitor of HIV RTE, so it blocks only HIV reverse transcriptase, not require activation by host enzyme, also cause less drug interaction and side effects

  
• NNRTI drugs


  • Nevirapine
  • Delaviridine

  
• Nevirapine


  • Absorbed orally, cross BBB, it reduces viral transmission during pregnancy
  • Side effects: Steven-Johnson syndrome, fatal hepatotoxicity, enzyme inducer so increases metabolism of other antiviral drugs