Antiviral agents

Question 1

Influenza treatment

Answer 1

Vaccine&raquo_space;
Only treat most fragile patients
must be given within the first 48 hours, decreases course by 1 day
Higher likelihood of resistance

Question 2

Amantadine

Answer 2

Antiviral RNA - Influenza A
Membrane protein M2 uncoating
Recently high levels of resistance (1 SNP)

Question 3

Neuraminidase inhibitors

Zanamavir, Oseltamivir

Answer 3

Prevent release of new virons from cell
Sialic acid derivatives - bind where sialic acid binds = antagonist
Prophylaxis, 80% effective in preventing

Question 4

Zanamivir

Answer 4

Not oral
dry powder for inhalation
cough and dry throat, bronchospasm
locally administered, no renal effects

Question 5

Oseltamivir

Answer 5

Oral dosing - can cause GI effects

Question 6

Acyclovir and Famciclovir

Answer 6

guanine nucleoside analogs (artificial base) = inhibit viral DNA polymerase
drugs phosphorylated by viral thymidine-kinase
used for HSV-1 and HSV-2, VZV

Question 7

Acyclovir

Answer 7

poor oral availability
need high dosing 3-5x/day
distribute to all tissues and CNS (herpes encephalitis)
renal excretion - worry about renal toxicity
Not 1st line!

Question 8

Famciclovir

Answer 8

Well absorbed orally - GI side effects
Better to use
Prodrug converted to penciclovir activated triphosphate and block DNA polymerase chain terminator

Question 9

Interferon

Answer 9

Combination with ribavirin for HepC treatment

Question 10

Interferon overview

Answer 10

Natural proteins produced by the cells of immune system in response to challenges by foreign agents (viruses, bacteria)
Anti-viral and immune actions
alpha and beta for viral infection

Question 11

Interferon mechanism of action

Answer 11

bind to host cell receptor, NOT TO VIRUS itself
stimulate the host immune system
Induction of enzymes
Inhibition of translation

Question 12

PEG-interferon

Answer 12

used in combo with ribavirin for HepC
extended 1/2 life, give once a week
cure almost 1/2 of HepC

Question 13

Simeprevir

Answer 13

NS3/4 Protease inhibitor
Post-translational processing of polyprotein
cannot cut the protein into small pieces
CYP450 metabolism liver precautions/drug interactions

Question 14

Sofosbuvir

Answer 14

NS5B RNA-dependent RNA polymerase inhibitor
Renal elimination
P-glycoprotein transporter

Question 15

Hepatitis C treatment

Answer 15

Need 2 drugs to prevent development of resistance!

Question 16

Emtricitabine (NRTI)

Answer 16

Nucleoside Reverse transcriptase inhibitors
phosphorylated intracellularly
Incorporated into DNA and terminate elongation, inhibit DNA polymerase
Excreted by kidneys
Toxic effects uncommon - lactic acidosis

Question 17

Efavirens (NNRTI)

Answer 17

Non-nucleotide reverse transcriptase inhibitor

Question 18

Atazanavir (PI)

Answer 18

Protease inhibitor

Prevent cleavage of viral proteins

Question 19

Dolutegravir (INTI)

Answer 19

Integrase inhibitor

Prevent integration of viral DNA into host DNA1

Question 20

Principles of Antiretroviral therapy

Answer 20

Need multiple drugs at once due to drug resistance with monotherapy - because RT makes many mutations
Combination pills are now available to prevent compliance problems

Question 21

Triple drug regimen

Highly active antiretroviral therapy (HAART) aka cART

Answer 21

NEED TO BE USED
transmission depend on the viral load, if you suppress it you decrease transmission
Combine of NRTIs w/ NNRTIs or PIs