Flashcards in Pharm: Antivirals Deck (17):
Why is acyclovir more selective than other anti-virals?
In order to acyclovir to be activated, it must be phosphorylated by viral kinases (thymidine kinase). This means that the drug will only be active in cells that are infected by viruses, minimizing side effects in the body.
Name 3 viruses that can be treated with acyclovir.
1. Herpes Simplex
2. Epstein Barr
3. Varicella Zoster
List 2 indications for valacyclovir.
Recurrent genital herpes infection
Recurrent varicella zoster infection
List 2 indications for famciclovir.
1. Acute herpes zoster
2. Recurrent genital herpes
What is the drug of choice for herpes encephalitis?
It is usually an infection with HSV-1 (adults) or HSV-2 (infants) so the drug of choice is acyclovir.
How is ganciclovir metabolized to an active form inside host cells.
Phosphorylated by CMV protein kinase and is a guanosine analog that inhibits DNA polymerase of CMV.
How does cidofovir have selective toxicity?
Activated by intracellular enzymes of host cells. However, even though it can be activated in uninfected cells the drug has a 1000x higher affinity for inhibiting viral DNA polymerase than human DNA polymerase.
List 4 viruses treated by foscarnet and what is unique about the metabolism of foscarnet?
This anti-viral does not need to be activated by phosphorylation. It can inhibit viral DNAP, RNAP, or HIV's reverse transcriptase.
What is the CDCs guidelines for treating influenza in adults?
Zanamivir if older than 7
Oseltamivir if older than 1
Amantadine for "flu A" if older than 1
Rimantidine for "flu A" in adults only
What is the MOA of neuraminidase inhibitors?
Neuraminidase is a viral enzyme that cleaves sialic acid from the host cell to allow formed viruses to bud and be released to the extracellular matrix.
NA inhibitors prevent the release of new viruses.
What is the site of action of palivizumab?
Binds to the fusion protein of Respiratory Syncytial Virus (RSV) to prevent entry of viruses into host cells.
How is palivizumab dosed?
It is a prophylaxis for RSV and is given intramuscular several times a month during RSV season.
Who should avoid contact with people taking ribavirin and why?
Pregnant women should avoid contact with people taking ribavirin because it is teratogenic.
It acts as a guanosine analog that inhibits viral nucleic acid synthesis but can also have effects on a developing fetus. The drug can be inhaled by a pregnant patient.
Why is selective toxicity more difficult for viruses than bacteria?
Viruses replicate using host cell machinery resulting in fewer differences between viruses and humans.
What are two blood related adverse effects of ganciclovir?
1. Leukopenia (low WBC count)
2. Thrombocytopenia (low platelets)
What is monitored to determine the duration of foscarnet action?
Foscarnet is cleared by the kidneys and is directly proportional to the clearance of creatinine kinase.