Antivirals Notes Flashcards
1) All antivirals are ……
2) No antivirals are ……
1) All are virustatic
2) None are virucidal
What type of intracellular parasites are viruses?
obligate intracellular parasites
Finish the sentence: As viruses utilise host cell enzymes to replicate……
….there are limited viral proteins that are targets for drugs
What is a common side effect to host cells?
toxicity to host cell
Are antivirals used in a) a minority or b) a majority of viral infections?
MINORITY
Antivirals a) DO b) DO NOT
eradicate virus from latently infected cells (Herpes)
b) DO NOT
True or False: Several stages of the life cycle are targets for antivirals (intracellular stages)?
TRUE
Do antivirals have a greater effect on a) host cell function or b) viral replication?
b) Viral replication
Most antivirals are what type of analogues?
nucleoside analogues
What do nucleoside analogues do?
they inhibit nucleic acid synthesis
Types of antiviral therapy:
What is prophylaxis?
To prevent infection
What is pre-emptive therapy?
It is when there is evidence of infection detected before symptoms
Name 4 types of antiviral therapy:
1) Prophylaxis
2) Pre-emptive therapy
3) Overt disease
4) Suppressive therapy
What is suppressive therapy?
it keeps viral replication below rate at which tissue damage occurs in an asymptomatic infected patient (HIV)
What is overt disease? (This wasn’t in notes)
A host-parasite interaction that results in some injury to the tissues of the host. (This was not in notes)
Antivirals for HSV: With what types of presentations of HSV are antivirals used?
- Mucocutaneous: Oral/ Genital/ Eye/ Skin
- Encephalitis
- Immunocompromised- any site
When are antivirals used in someone who presents with chickenpox (VZV)?
- When it affects neonate/ immunocompromised/ pregnant
- Immunocompromised adult: only effective if the treatment is begun within 24h
When are antivirals useful in someone who presents with shingles (VZV)?
only decreases post-herpetic neuralgia in immunocompetent host if begun within 72h
Name some of the antiviral treatments and their route of administration in HSV + VZV:
- Aciclovir: Oral/ IV/ Eye ointment/ cream
- Valaciclovir: Oral
- Famciclovir: Oral
- Foscarnet: IV
(Aciclovir like drugs are only active in herpes infected cells (low toxicity for normal cells) )
Describe Aciclovir’s mode of action: (4 points)
- Aciclovir is converted by viral thymidine kinase to ACVMP
- ACVMP then converted by host cell kinases to ACV-TP
- ACV-TP in turn completely inhibits + inactivates HSV-specific DNA polymerase
- Preventing further viral DNA synthesis without affecting normal cellular processes
Antivirals + CMV ( cytomegalovirus):
-All available drugs for CMV have significant toxicity,
when should antivirals be used to treat CMV?
- Only treat life/ sight threatening CMV infections
- May be used to treat neonates with symptomatic congenital CMV infection
Name 4 antivirals used in the treatment of CMV and give their routes of administration:
- Ganciclovir: IV/ ocular implant
- Valganciclovir: Oral
- Cidofovir: IV
- Foscarnet: IV
Antivirals+ HIV: What is the type of antiviral therapy used in HIV?
Combination anti-retroviral therapy (cART)
How has cART transformed HIV care?
- Restoration of immune function in AIDS
- Decrease in opportunistic infections
What are the antivirals used for chronic Hepatitis B?
- Pegylated interferon alpha (subcutaneous)
* Nucleoside analogues – Tenofovir / Adefovir / Entecavir / Lamivudine / Emtricitabine/ Telbivudine
What is the length of time antivirals are used for in Chronic Hepatitis C?
often 12-48 weeks
What are the 2 antiviral therapies used for Chronic Hepatitis C?
oPeglycated interferon alpha (subcutaneous) + ribavirin (oral)
oAs above plus protease inhibitor (telaprevir / boceprevir)
In what respiratory infections are antivirals used?
- Influenza A / B
- Respiratory Syncytial Virus
State the antiviral treatment used in Influenza A / B:
• Oseltamivir (Tamiflu) or Zanamivir
o Role in both treatment + prophylaxis
o Should start within 48 hours of symptom onset / contact
State the antiviral treatment used in Respiratory Syncytial virus:
Ribavirin (rarely indicated)
What are the 2 categories of antiviral resistance that you can get?
Phenotypic & Genotypic
Describe phenotypic resistance to antivirals:
• Phenotypic – Virus can grow in presence of compound (HSV)
Describe Genotypic resistance to antivirals:
• Genotypic – Sequence genome + identify resistance associated mutations (HIV)
When should you suspect resistance to herpes virus in the immunocompromised?
If no response within 7 days
If HSV + CMV are both resistant to aciclovir, what is usually effective next?
Foscarnet is usually effective
When is HIV resistance testing performed?
At diagnosis/ failing therapy
