Anti-Viral Therapy ✅ Flashcards
What are the limitations of anti-viral therapy?
- Hard to achieve drug anti-viral selectivity
- Virus often widespread before symptoms present and treatment initiated
Why is drug anti-viral selectivity harder to achieve than for anti-bacterial drugs?
Viral replication depends on host cellular processes
What do anti-viral agents target?
Different stages in virus-specific replication
What stages in virus-specific replication can be targeted by anti-virals?
- Entry into the cell
- Transcription
- Nucleic acid and protein synthesis
- Package and release of virions
Of what type are most anti-virals in clinical use?
Nucleoside analogues
How do nucleoside analogues work?
They look like the basic nucleotides, but have been chemically altered to stop viral replication
How is aciclovir able to induce selective toxicity against viruses?
Because it is a pro-drug which requires viral enzyme to help convert it to the active form
How is aciclovir converted to the active form?
By phosphorylation
What is aciclovir used to treat?
- Herpes simplex virus (HSV)
- VZV
How is valaciclovir administered?
Orally
What happens once valaciclovir is absorbed into the blood?
It becomes hydrolysed to aciclovir
What is gangciclovir used to treat?
CMV
Why is ganciclovir specifically used to treat CMV?
It requires phosphorylation using an enzyme present in CMV
How does the toxicity of ganciclovir compare to aciclovir?
It is more toxic
Why is ganciclovir more toxic than aciclovir?
Host cells can also add the phosphate group to ganciclovir
