Antiviral drugs

Question 1

guanosine analog drugs

Answer 1

acyclovir, valacyclovir, famciclovir, ganciclovir

Question 2

cytosine analog drugs

Answer 2

cidofovir (cytosine monophosphate analog)

Question 3

pyrophosphate analog drugs

Answer 3

Foscarnet

Question 4

sugar analog drugs

Answer 4

Ribavirin (D-ribose analog)

Question 5

neuraminidase inhibitors

Answer 5

oral: oseltamivir (tamiflu), baloxavir
aerosolized: zanamivir
IV: peramivir

Question 6

acyclovir

Answer 6

Analog of guanosine - chain terminator, first to enter clinical use for HSV and VZV infections; poorly absorbed orally. Active ONLY in infected cells (unlike ganciclovir).

HSV must add the first phosphate group with viral thymidine kinase - if HSV loses its thymidine kinase, becomes resistant to acyclovir.

side effects: agitation, renal issues due to crystallization in the kidney.

Question 7

valacyclovir

Answer 7

Analog of guanosine - chain terminator, used for HSV, VZV. Better absorbed through small intestine than acyclovir due to L-valine.

side effects: agitation, renal issues due to crystallization in the kidney.

Question 8

ganciclovir

Answer 8

Guanosine analog chain terminator; achieves much higher levels in infected cells than acyclovir. Used primarily for CMV retinitis, CMV colitis, or severe disseminated infections.
UNLIKE Acyclovir: More efficient with viral TK, but does not require viral TK. Uninfected cells may be affected = potentially toxic to rapidly proliferating cells in the bone marrow = leukopenia. CBC should be checked while on this med.

Question 9

cidofovir

Answer 9

Cytosine-monophosphate analog chain terminator. Used for CMV retinitis, resistant HSV and VZV infections, and invasive adenovirus infections in immunocompromised individuals. NOT reliant on viral TK, thus good for resistant HSV.

Can cause nephrotoxicity & fanconi-type syndrome with proteinuria and glucosuria.

Question 10

foscarnet

Answer 10

Pyrophosphate analog that causes chain termination bc cannot be incorporated into backbone. Directly binds and inhibits DNA pol.
Used for CMV retinitis, resistant HSV & VZV infections. NOT reliant on viral TK, thus good for resistant HSV.
Side effects of nausea and nephrotoxicity.

Question 11

ribavirin

Answer 11

drug that is similar to D-ribose, chain terminator because base is faulty (nonsense base). Aerosolized ribavirin is given to infants/children with severe lower resp infections due to RSV. Also used as adjunct treatment for Hep C and viral hemorrhagic fevers (Lassa fever).

Question 12

oseltamivir

Answer 12

Tamiflu; neuraminidase inhibitor that is given orally in the first 1-2 days of symptoms. Also widely used for prophylaxis in outbreaks. Inhibits flu virus from being able to escape respiratory cells and spread to others by inhibiting the neuraminidase enzyme which is required for the virus to cleave sialic acid and exit the cell.
(Sialic acid is present in higher concentrations in the respiratory track to assist with mucus viscosity and elasticity.)

Side effects: headache, nausea, vomiting

Question 13

baloxavir

Answer 13

neuraminidase inhibitor that is given orally in the first 1-2 days of symptoms. Also widely used for prophylaxis in outbreaks. Inhibits flu virus from being able to escape respiratory cells and spread to others by inhibiting the neuraminidase enzyme which is required for the virus to cleave sialic acid and exit the cell.
(Sialic acid is present in higher concentrations in the respiratory track to assist with mucus viscosity and elasticity.)

Side effects: headache, nausea, vomiting

Question 14

zanamivir

Answer 14

neuraminidase inhibitor that is aerosolized and inhaled. Inhibits flu virus from being able to escape respiratory cells and spread to others by inhibiting the neuraminidase enzyme which is required for the virus to cleave sialic acid and exit the cell.
(Sialic acid is present in higher concentrations in the respiratory track to assist with mucus viscosity and elasticity.)

Side effects: localized - bronchospasm

Question 15

peramivir

Answer 15

Neuraminidase inhibitor that is given via IV. Inhibits flu virus from being able to escape respiratory cells and spread to others by inhibiting the neuraminidase enzyme which is required for the virus to cleave sialic acid and exit the cell.
(Sialic acid is present in higher concentrations in the respiratory track to assist with mucus viscosity and elasticity.)

side effects: headache, nausea, vomiting

Question 16

direct acting anti-HCV agents

Answer 16

target nonstructural proteins that are vital for viral replication - NS3/4A, NS5A, NS5B. These drugs are phosphorylated in the cell and incorporated into the HCV viral RNA strand causing premature truncation.

Rare side effects: cough/dyspnea. bradycardia

Question 17

famciclovir

Answer 17

Guanosine analog chain terminator with 2 acetyl groups which increases fat-solubility and makes it well absorbed with long half life in the body. Converted to penciclovir in body. Used for HSV and VZV infections.

Question 18

simeprevir

Answer 18

HCV drug that inhibits protease NS3/4A. This causes inability to cleave the HCV polyprotein thus inability for the virus to replicate.

Question 19

sofosbuvir (Harvoni) and Ribavirin

Answer 19

HCV drugs - NS5B polymerase inhibitors. Prevent replication complex from forming from cleaved proteins and thus prevents viral replication.

Question 20

ledipasvir (Harvoni)

Answer 20

HCV drug that inhibits NS5A thus inhibiting viral replication.