Antivirals Flashcards
What is the genetic makeup of Herpesviruses? Enveloped?
dsDNA
Enveloped
What is the common MOA of antivirals to treat herpes?
Partes the DNA pol in some way
What are the six steps of the viral life cycle?
- Attachment
- entry
- mRNA production
- Protein and genome synthesis
- Virion assembly
- Egress
What is the only phase of the viral life cycle in which antivirals are active?
Lytic phase
What is the goal of treatment with antivirals?
Speed healing and increase time between outbreaks
What are the four herpes viruses that have antiviral therapy available for them?
HSV-1
HSV-2
CMV
VZV (HSV-3)
What disease does HSV-1 cause? HSV-2? 3? CMV?
1 = oral herpes 2 = genital herpes 3 = varicella CMV = pneumonitis, gastroenteritis
What is the MOA of acyclovir?
Nucleoside analog that inhibitor of herpesvirus DNA polymerase.
(It is both a competitive inhibitor and substrate for the polymerase)
Does Acyclovir act via competitive or non-competitive inhibition?
Competitive inhibition
What happens once Acyclovir is incorporated into the viral DNA chain?
Chain terminates
What is the way in which Acyclovir develops resistance?
Mutation of thymidine kinase gene
For what two diseases is Acyclovir given PO?
Genital herpes
Varicella zoster
What are the four diseases in which Acyclovir is given via IV administration?
- Severe or disseminated mucocutaneous disease
- Neonatal infections
- HSV encephalitis
- VZV in immunocompromised pts
What are the side effects of Acyclovir?
HA
N/v/d
Reversible crystalline nephrotoxicity
What type of drugs should Acyclovir not be given with?
Any that damage the kidney
What is valacyclovir?
Prodrug of acyclovir (attached to a Valine moiety)
True or false: acyclovir has a high oral bioavailability
False–low
What is the MOA of valacyclovir?
Inhibitor of herpesvirus DNA
polymerase (same as acyclovir)
What are the diseases that Valacyclovir is given?
Primary and recurrent genital herpes
Zoster
Orolabial herpes
Varicella in older children
What is the MOA of Foscarnet?
DNA pol inhibitor–Foscarnet binds the site normally occupied by pyrophosphate, thereby blocking pyrophosphate
release and ultimately the catalytic cycle
What is the major difference between acyclovir and Foscarnet?
Foscarnet does not require prior phosphorylation by thymidine kinase
What type of molecule is Acyclovir and Valacyclovir?
Nucleoside
What type of molecule is foscarnet?
Phosphonoformic acid (analog of pyrophosphate)
What is the route of administration of Foscarnet?
IV
How is resistance to Foscarnet brought about?
Mutation in DNA pol
What is Foscarnet used to treat?
HSV and VZV infections that are resistant to acyclovir
CMZ retinitis
What are the adverse effects of Foscarnet?
Renal impairment
Changes in Ca, PO3, K, or Mg levels
What drugs should be avoided with Foscarnet?
Nephrotoxic
What is the drug used to treat CMV? Why this instead of Acyclovir?
Ganciclovir
Is activated more readily by UL97 (CMV gene)
What type of molecule is Ganciclovir?
Acyclic guanosine analog
What is the MOA of Ganciclovir?
The triphosphate form of ganciclovir is a competitive inhibitor for the viral DNA polymerase and chain terminator when incorporated into the newly synthesized viral DNA genomes
How is Ganciclovir administered?
PO or IV
What is the bioavailability of Ganciclovir?
Poor
How is resistance to Ganciclovir brought about?
Mutations in the UL97 gene
What is Ganciclovir used to treat if given IV?
CMV retinitis
CMV colitis, pneumonitis, and esophagitis
What is Ganciclovir used to treat if given IV follow by PO?
Reduced the risk of CMV transplant risk
What is Ganciclovir used to treat if given intraocularly?
CMV retinitis
What are the adverse effects of Ganciclovir?
Myelosuppression
CNS toxicity
What is the MOA of Valganciclovir?
competitive inhibitor for the viral DNA polymerase (same as Ganciclovir)
What is the prodrug form of Ganciclovir? How is this made into a prodrug?
Valganciclovir
L-valyl ester of ganciclovir
What is the major advantage of Valganciclovir over Ganciclovir?
Can be given orally
What is valganciclovir used for?
CMV retinitis in AIDS
Prevent CMV disease in pts with transplants
What type of chemical is Trifluridine?
Fluorinated nucleoside
What is the MOA of Trifluridine?
Competitive inhibitor of thymidine for incorporation into newly synthesized genomes
What are the therapeutic indications for Trifluridine?
Ocular administration to treat keratoconjunctivitis and recurrent epithelial keratitis d/t HSV-1 and HSV-2
Why is Foscarnet used in cases of resistance to Acyclovir?
Acts farther down the chain, and does not need to be phosphorylation by viral enzymes, which can mutate
What is the MOA of Penciclovir?
Inhibits DNA pol for HSV
What is the family and genetic makeup of the influenza virus? Enveloped?
Orthomyxovirus
-ssRNA
Enveloped
What disease does influenza C usually cause?
Mild respiratory illness
What disease does influenza B usually cause?
Mild respiratory illness, but occasionally more severe
How soon after initial symptoms must antivirals for the flu be given?
48 hours
What is the most common complication of influenza?
Pneumonia
What type of molecule is Oseltamivir? How is it metabolized to its active form?
Sialic acid analog that is metabolized to active compound by hepatic esterases
What is the MOA of Oseltamivir? What does this cause?
Binds to the active side of neuraminidase to inhibit its function
This causes clumping of the progeny virions
on the surface of infected cells
How is Oseltamivir administered?
Orally
How is resistance to Oseltamivir brought about?
Point mutations in the hemagglutinin or neuraminidase genes
Which influenza strains if Oseltamivir given?
A and B strains
What are the adverse effects of Oseltamivir?
N/v/d
HA
CNS events
What type of chemical is Zanamivir? What is this used to treat?
Sialic acid used to treat the flu
What is the MOA of Zanamivir?
Competitively and reversibly binds to the influenza
neuraminidase active site and inhibits its function
How is Zanamivir administered?
To oropharynx and lungs by inhalation
How common is resistance to Zanamivir?
Rare
What is the difference in the indications for Zanamivir vs Oseltamivir?
Zanamivir is only for 7+
What are the adverse effects of Zanamivir?
Cough, bronchoconstriction
What is the MOA of Peramivir? What is it used for? Adverse effects?
Neuraminidase inhibitor
Acute, uncomplicated flu
CNS effects
How is Peramivir administered?
Inhalation
What is the chemical structure and MOA of Amantadine?
Symmetric tricyclic amines
Inhibits Influenza A M2 protein that is required for nucleocapsid release
What is the chemical structure and MOA of Rimantadine?
Symmetric tricyclic amines
Inhibits Influenza A M2 protein that is required for nucleocapsid release
What are amantadine and rimantadine used to treat?
Flu A
What is the viral family, genetic makeup, and enveloped status of RSV?
Paramyxoviridae
-ssRNA
Enveloped
What is RSV?
Bronchiolitis and pneumonia in children, ILI in adults
What is the drug that is used to treat RSV? How is this administered?
Ribavirin–inhalable
What type of chemical is Ribavirin? MOA?
Guanosine analog that interfere with the synthesis of guanosine triphosphate, and inhibits mRNA capping
What is the antiviral for treating Hep C? (not the new curing drug)
Ribavirin
What are the adverse effects of Ribavirin?
Hemolytic anemia
What are the contraindications to Ribavirin?
Prego
anemic
Renal disease
What is the viral family, genetic makeup and enveloped status of HCV?
Flaviviridae
+ssRNA
Enveloped
Which genotype of HCV is the least responsive to traditional treatment regimes
1
What is the viral family, genetic makeup and enveloped status of HAV?
Picornaviridae
RNA
Non-enveloped
What is the viral family, genetic makeup and enveloped status of HBV?
Hepadnaviridae
dsDNA
Enveloped
What is the viral family, genetic makeup and enveloped status of HEV?
Hepeviridae
+ssRNA
Non-enveloped
What is the protease that cleaves the viral polyprotein, which is a direct translation of the ssRNA of HCV? Which drugs inhibit this?
HCV NS3/4A
Paritaprevir
Simeprevir
What are the enzymes that take the +ssRNA of HCV, and turn it into a -ssRNA template for the production of new viral particles? Which drugs inhibit this?
HCV NS5B (RdRp) HCV NS5A
Sofosbuvir and Dasabuvir
What are the two drugs that inhibit the virion assembly?
Ledipasvir
Ombitasvir
What is the MOA of Paritaprevir? How is it administered?
Protease inhibitor for HCV infections
PO administration
What are the adverse effects of Paritaprevir?
Asthenia
Fatigue
How is resistance to Paritaprevir brought about?
Specific NS3 gene substitution
What is the MOA of Simeprevir? How is it administered?
Protease inhibitor in HCV infections
PO administration
What are the adverse effects of Simeprevir?
Rash/pruitis
How is resistance to Simeprevir brought about?
Mutations in NS3 gene
What is the MOA of Ledipasvir? How is it administered?
Nucleotide analog that inhibits HCV NS5A
PO administration
What are the adverse effects of Ledipasvir?
Diarrhea, HA
How does resistance to Ledipasvir come about?
NS5A gene substitution
What is the MOA of Ombitasvir? How is it administered? Adverse effects?
Nucleotide analog that inhibits HCV NS5A
PO administration
Myasthenia
What is the MOA of Sofosbuvir? How is it administered? Adverse effects?
Nucleotide analog prodrug that is incorporated into HCV’s RNA and breaks it
PO
Anemia, ILI
What is the MOA of Dasabuvir? How is it administered? Adverse effects?
Non-nucleoside inhibitor of RNA-dependent-RNA pol in HCV
PO administration
Fatigue