Pharm: Antivirals

Question 0

Name 3 viruses that can be treated with acyclovir.

Answer 0

1. Herpes Simplex
2. Epstein Barr
3. Varicella Zoster

Question 1

Why is acyclovir more selective than other anti-virals?

Answer 1

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.

Question 2

List 2 indications for valacyclovir.

Answer 2

Recurrent genital herpes infection

Recurrent varicella zoster infection

Question 3

List 2 indications for famciclovir.

Answer 3

1. Acute herpes zoster

2. Recurrent genital herpes

Question 4

What is the drug of choice for herpes encephalitis?

Answer 4

It is usually an infection with HSV-1 (adults) or HSV-2 (infants) so the drug of choice is acyclovir.

Question 5

How is ganciclovir metabolized to an active form inside host cells.

Answer 5

Phosphorylated by CMV protein kinase and is a guanosine analog that inhibits DNA polymerase of CMV.

Question 6

How does cidofovir have selective toxicity?

Answer 6

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.

Question 7

List 4 viruses treated by foscarnet and what is unique about the metabolism of foscarnet?

Answer 7

1. HSV
2. VZV
3. CMV
4. EBV
5. HHV-6
6. HBV
7. HIV

This anti-viral does not need to be activated by phosphorylation. It can inhibit viral DNAP, RNAP, or HIV’s reverse transcriptase.

Question 8

What is the CDCs guidelines for treating influenza in adults?

Answer 8

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

Question 9

What is the MOA of neuraminidase inhibitors?

Answer 9

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.

Question 10

What is the site of action of palivizumab?

Answer 10

Binds to the fusion protein of Respiratory Syncytial Virus (RSV) to prevent entry of viruses into host cells.

Question 11

How is palivizumab dosed?

Answer 11

It is a prophylaxis for RSV and is given intramuscular several times a month during RSV season.

Question 12

Who should avoid contact with people taking ribavirin and why?

Answer 12

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.

Question 13

Why is selective toxicity more difficult for viruses than bacteria?

Answer 13

Viruses replicate using host cell machinery resulting in fewer differences between viruses and humans.

Question 14

What are two blood related adverse effects of ganciclovir?

Answer 14

1. Leukopenia (low WBC count)

2. Thrombocytopenia (low platelets)

Question 15

What is monitored to determine the duration of foscarnet action?

Answer 15

Foscarnet is cleared by the kidneys and is directly proportional to the clearance of creatinine kinase.

Question 16

What is the major toxicity of zanamavir and for what population should in NOT be prescribed?

Answer 16

Zanamivir is a neuraminidase inhibitor used to treat the flu.

Can cause bronchospasm and a general decline in respiratory function.

For this reason it should not be used in patients with COPD or asthma.