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
What is the difference between valganciclovir and ganciclovir?
Valganciclovir is better absorbed orally
What anti-viral is active against influenza?
Oseltamivir
How is oseltamivir active against influenza?
It inhibits newly formed influenza virions from being released from host cells
How does oseltamivir inhibit the release of newly formed influenza virions?
By inhibiting viral neuraminidase (surface proteins)
What kind of anti-virals are used to treat HIV?
Antiretrovirals
What are the classes of anti-retrovirals?
- Nucleoside analogue reverse transcriptase inhibitiors (NRTs)
- Non-nucleoside analogue reverse transcriptase inhibitors (NNRTs)
- Protease inhibitors (PI)
- Fusion inhibitors (FI)
- Integrase inhibitors
Give an example of a NRTI
AZT
Give an example of a NNRTI?
Nevirapine
Give an example of a protease inhibitor
Ritonavir
Give an example of a fusion inhibitor
Maraviroc
Give an example of a integrase inhibitor
Raltegravir
What can limit the tolerability of antiretrovirals in HIV?
Side effects
How do protease inhibitors exert their side effects?
By affecting glucose and lipid metabolism
What can lead to drug resistance against antiretrovirals used in HIV?
Mutations in the virus
How is resistance to anti-retrovirals in HIV prevented?
- Combination treatment
- Good adherence
