Antivirals

Question 1

Acyclovir

Answer 1

Nucleoside Analogue

MOA: requires phosphorylation by viral thymidine kinase -> inhibits viral DNA polymerase -> chain termination upon incorporation into viral DNA

Rx: Oral -> genital herpes, VZV, IV -> neonate infections, HSV encephalitis, VZV in immunocompromised

Poor oral availability

Question 2

Valacyclovir

Answer 2

Prodrug of acyclovir.

3-5x ↑ oral bioavailability

Rx: genital herpes, Varicella, Zoster, orolabial herpes

Question 3

Foscarnet

Answer 3

Pyrophosphate analogue

MOA: occupies spot of pyrophosphate and blocks its release -> inhibits viral DNA polymerase (No requirement for thymidine kinase)

Rx: HSV and VZV that are resistant to acyclovir, CMV retinitis / colitis / esophagitis

IV use only

Question 4

Ganciclovir

Answer 4

Guanosine analogue
MOA: inhibits viral DNA polyermase -> chain termination

requires phosphorylation by viral kinase enzyme (CMV UL97 100x more effecient than acyclovir)

Rx: CMV retinitis (IV / intraocular), CMV colitis / pneumonits / esophagitis (IV), transplant recipients (↓ risk of CMV w/ IV then oral)

Poor oral bioavailability

Question 5

Valganciclovir

Answer 5

Prodrug of ganciclovir

Rx: CMV retinitis, transplant recipients (↓ risk of CMV in heart, kidney, pancreas transplants)

Higher bioavailability than oral ganciclovir

Question 6

Oseltamivir

Answer 6

Sialic Acid analogue
MOA: binds to and inhibits neuraminidase -> stops spread of virions through respiratory tract

Rx: Influenza A and B, within 48 hours, 1+ yoa

Oral administration

Question 7

Zanamivir

Answer 7

Sialic Acid analogue
MOA: binds to and inhibits neuraminidase -> stops spread of virions through respiratory tract

Inhaled

Rx: Influenza A and B, within 48 hours, 7+ yoa

Question 8

Peramivir

Answer 8

Neuramindase Inhibitor

Rx: acute uncomplicated flu if symptomatic for less than 48 hours

IV administration

Question 9

Amantadine

Answer 9

Symmetric tricyclic amines
MOA: inhibits Influenza A M2 protein (ion channel forming protein)

Rx: Influenza A virus within 48 hours

Question 10

Rimantadine

Answer 10

Symmetric tricyclic amines
MOA: inhibits Influenza A M2 protein (ion channel forming protein)

Rx: Influenza A virus within 48 hours

Question 11

Ribavirin

Answer 11

Guanosine analogue
MOA: phosphorylated by adenosine kinase -> interfieres w/ guanosine triphosphate synthesis -> inhibits viral mRNA capping -> inhibits RdRp of RSV and HepC

RSV: inhaled, HCV: oral

Rx: RSV, chronic HepC (comboTx)

Question 12

Paritaprevir

Answer 12

Protease Inhibitor
MOA: inhibits HCV NS3/4A protease (cleavage of immature viral polypeptides)

Rx: Chronic HepC
(ComboTx)

Question 13

Simeprevir

Answer 13

Protease Inhibitor
MOA: MOA: inhibits HCV NS3/4A protease (cleavage of immature viral polypeptides)

Rx: Chronic HepC
(ComboTx)

Question 14

Ledipasvir

Answer 14

NS5A Inhibitor
MOA: inhibits HCV NS5A protein (viral RNA replication and virion assembly)

Rx: Chronic HepC
(ComboTx)

Question 15

Ombitasvir

Answer 15

NS5A Inhibitor
MOA: inhibits HCV NS5A protein (viral RNA replication and virion assembly)

Rx: Chronic HepC
(ComboTx)

Question 16

Sofosbuvir

Answer 16

RNA Polymerase Inhibitor
MOA: incorporated into RNA by RdRp -> chain termination

Rx: Chronic HepC
(ComboTx)

Question 17

Dasabuvir

Answer 17

RNA Polymerase inhibitor
MOA: targets palm domain of RdRp -> halt of viral life cycle before RNA synthesis

Rx: Chronic HepC
(ComboTx)