Antimicrobials: Antiviral Drugs

Question 1

Acyclovir is used to treat

Answer 1

HSV infections

Question 2

Acyclovir is a ________ analog

Answer 2

guanisine nucleoside analog

Question 3

Acyclovir activation

Answer 3

1. acyclovir monophosphate via virus encoded thymidine-kinase
2. acyclovir triphosphate by cellular kinases

Question 4

Acyclovir is first converted to acyclovir monophosphate via

Answer 4

virus encoded thymidine-kinase

Question 5

Acyclovir is converted to __________ via virus encoded thymidine-kinase

Answer 5

acyclovir monophosphate

Question 6

Acyclovir is converted to __________ by cellular kinases

Answer 6

acyclovir triphosphate

Question 7

Acyclovir is converted to acyclovir triphosphate by ________

Answer 7

cellular kinases

Question 8

What three oral drugs are used to treat HSV and VZV infections

Answer 8

1. Acyclovir
2. Valacyclovir
3. Famciclovir

Question 9

What must happen for acyclovir and ganciclovirto become active

Answer 9

it must be triphosphorylated

Question 10

Acyclovir functions by

Answer 10

Once acyclovir is converted to a triphosphate it then used by viral DNA polymerase and incorporated into viral DNA. Incorporation of acyclovir triphosphate into viral DNA halts DNA synthesis

Question 11

What is the rate determining activation step in the acyclovir reaction

Answer 11

Herpesvirus-encoding thymidine kinase phosphorylation of acyclovir to acyclovir monophosphate

Question 12

Absence of what viral enzyme in HSV or VZV confers resistance t acyclovir

Answer 12

absence of thymidine-kinase confers resistance to acyclovir

Question 13

Cidofovir

Answer 13

cidofovir does not require phosphorylation by the viral kinase and is thus active against acyclovir or ganciclovir resistant HSV, CMV, VZV

Question 14

foscarnet

Answer 14

foscarnet is active against acyclovir or ganciclovir resistant HSV, CMV, VZV

Question 15

cidofovir and foscarnet directly inhibit

Answer 15

viral DNA polymerase

Question 16

Daily valacyclovir is used as

Answer 16

suppressive therapy for multiple yearly episodes of recurrence of HSV

Question 17

valacyclovir has improved _____ bioavailability

Answer 17

valacyclovir has improved oral bioavailability

Question 18

IV acyclovir treats

Answer 18

1. serious HSV and VZV infections
2. HSV encephalitis
3. neonatal HSV

Question 19

famcyclovir and valacyclovir are preferred treatments for VZV due to

Answer 19

famcyclovir and valacyclovir are preferred treatments for VZV due to superior activity and less frequent dosing

Question 20

______ and ______ are preferred treatments for VZV due to superior activity and less frequent dosing

Answer 20

famcyclovir and valacyclovir

Question 21

during active shingles infection, valacyclovir and famcyclovir are most effective if given within

Answer 21

during active shingles infection, valacyclovir and famcyclovir are most effective if given within 3 days of onset of symptoms

Question 22

HSV is prophylaxis important in

Answer 22

1. immunocompromised states

2. pregnant women with active recurrent genital herpes

Question 23

IV acyclovir can cause

Answer 23

1. interstitial nephritis or crystalline nephropathy
2. delerium
3. confusion
4. vertigo
5. hallucinations

Question 24

______ prevents renal side effects of IV acyclovir

Answer 24

adequate hydration

Question 25

ganciclovir is used for

Answer 25

hemorrhages and infiltrates of CMV retinitis

Question 26

CMV infections are more common with a CD4+ count

Answer 26

CMV infections are more common with a CD4+ count < 50

Question 27

Ganciclovir activation

Answer 27

1. CMV infections are more common with a CD4+ count < 50 | 2. converted to ganciclovir triphosphate by cellular kinases

Question 28

How does ganciclovir work

Answer 28

ganciclovir triphosphate incorporates into replicating viral DNA, halting synthesis

Question 29

valganciclovir has better ____ bioavailability

Answer 29

valganciclovir has better oral bioavailability

Question 30

valganciclovir or ganciclovir is indicated in

Answer 30

high-risk solid organ and bone marrow transplant recipients

Question 31

ganciclovir and valganciclovir are associated with

Answer 31

bone marrow supression

Question 32

ganciclovir and valganciclovir myelosuppression may be additive in patients receiving

Answer 32

zidovudine

Question 33

Foscarnet and cidofovir

Answer 33

do not require phosphorylation by the viral kinase - active against ganciclovir or acyclovir resistant HSV, CMV, VZV

Question 34

foscarnet side effects

Answer 34

1. renal insufficiency 2. hypocalcemia 3. hypomagnesemia 4. hypokalemia 5. seizures

Question 35

cidofovir and foscarnet

Answer 35

directly inhibit viral DNA polymerase

Question 36

Cidofovir is ______toxic

Answer 36

cidofovir is nephrotoxic

Question 37

Cidofovir side effects

Answer 37

1. proteinuria 2. azotemia 3. metabolic acidosis

Question 38

______ blocks the tubular secretion of cidofovir, limiting its toxic effects

Answer 38

probenecid

Question 39

_____ prevents excretion and increases plasma concentrations of many different drugs (e.g. penicillins, methotrexate, NSAIDs)

Answer 39

probenecid