Anti-Viral Drugs I Flashcards
The genomes of non-retroviruses are made of either
DNA or RNA
What are 3 examples of DNA viruses?
Herpes, Varicella, and Cytomegalovirus
Replicate inside host nuclei using virus-encoded machinery
DNA viruses
In DNA viruses, the viral genome is transcribed and translated by
Host proteins
A DNA virus that replicates through an RNA intermediate
HBV
What are two examples of RNA viruses?
Influena and Hepatitis A and C
(-)RNA genome serves as template for viral mRNA production
Influenza
In influenza, the genome is copied into a
(+) RNA intermediate
This (+) RNA intermediate is then used to produce more
(-) RNA genomes
(+) RNA genome is used directly as mRNA. The genome is copied to a (-) RNA intermediate, which is used to produce more (+) RNA genomes
Hepatitis
Analogs of naturally occurring nucleosides inhibit viral
DNA replication
All compete with natural nucleotides for binding viral DNA polymerase
Nucleoside analogs
Requires HSV thymidine kinase (TK) for first phosphaste
Acyclovir
Guanosine derivative that functions as a viral DNA replication inhibitor
Acyclovir
Acyclovir undergoes monophosphorylation by viral
Thymidine Kinase (HSV-TK)
Phosphorylation traps acyclovir within
Infected cells
The triphosphate form competes with dGTP to bind viral DNA polymerase
-Also acts as chain terminator
Acyclovir
Resistance to acyclovir is due largely to mutations in
HSV-TK and viral DNA polymerase
HSV-TK mutations cause cross-resistance to other drugs activated by
HSV-TK
A derivative of acyclovir that has increased bioavailability of the drug
Valacyclovir
Limited by renal insufficiency and CNS effects
-Use slow infusion rate
IV acyclovir
No evidence of teratogenic or carcinogenic effects despite nucleoside structure
Acyclovir
Drug Treatments for Herpes Simplex Virus (HSV) and Varicella Zoster Virus (VZV) are
Nucleoside analogs (acyclovir)
Which drugs do we use to treat Cytomegalovirus (CMV)?
Valganciclovir, ganciclovir, and letermovir
Valganciclovir and ganciclovir are both
Guanosine derivatives
The valyl protecting group in valganciclovir is removed at the
Intestinal wall
Taken orally
Valganciclovir
Given by IV
Ganciclovir
Ganciclovir is a prodrug that must be
Triphosphorylated
Adds the first phosphate to ganciclovir
Viral UL97 kinase
Binds viral polymerase competitively and causes chain termination
Ganciclovir
Ganciclovir resistance is caused by mutations in the viral
UL97
Approved in 2017 for CMV suppression during hematopoietic stem cell transplant (HSCT)
Letermovir
Inhibits the CMV DNA terminus complex required for viral packaging
Letermovir
Cleaves viral concatemers after DNA replication into monomers
Letermovir
Letermovir is an inhibitor and inducer of
CYP3A4 and other P450s
Contraindicated for use with pimozide, ergot alkaloids
Letermovir
Letermovir is also contraindicated for use with pitavastatin or simvastatin when co-administered with
Cyclosporine
Recommended treatments for first clinical episode for HSV and VZV
Acyclovir, valacyclovir, and famciclovir