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DD unit 3 > Antiviral review > Flashcards

Antiviral review Flashcards

1
Q

What are the major target for antiviral drugs from this unit? (4)

A

1 - Attachment and entry 2 - uncoating 3 - Nucleic acid synthesis 4 - Viral release

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2
Q

Which drug blocks the attachment and entry of HSV?

A

docosanol

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3
Q

Which drugs block the uncoating of influenza?

A

Amantadine and rimantadine

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4
Q

Which drug block the nucleic acid synthesis of HSV?

A

Acylovir, valacyclovir, penciclovir

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5
Q

Which drug block the nucleic acid synthesis of CMV?

A

Ganciclovir, valganciclovir, foscarnet, cidofovir

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6
Q

Which drugs prevent the release of influenza?

A

Neuraminidase inhibitors - zanamivir and oseltamavir

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7
Q

Describe the resistance of neuraminidase inhibitors.

A

Rare - can have mutations of neuraminidase of hemagluttinin

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8
Q

How is oseltamivir absorbed?

A

oral - 80% bioavailable

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9
Q

How is zanamivir absorbed?

A

inhalation - 10-20% of dose absorbed

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10
Q

How is oseltamivir eliminated?

A

tubular secretion - dose modified for renal insuficiency

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11
Q

How is zanamivir eliminated?

A

renal

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12
Q

What is the clinical use of zanamivir?

A

Started within 2 days of symptoms can shorten duration. Given to people >7 yo

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13
Q

What is the clinical use of oseltamivir?

A

Prophylactic - 70-90% effective at preventing flu. Give up to 48 hrs after start of infection can decrease severity and duration. Give to anyone >1 yo.

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14
Q

What are the adverse reactions of oseltamivir?

A

nausea, vomiting, abdominal pain some headache fatigue diarrhea. Pregnancy category C.

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15
Q

What are the adverse reactions of zanamivir?

A

Cough, bronchospasm, decrease in pulm function, nasal and throat discomfort. Pregnancy cat C

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16
Q

How does amantadine and rimantadine work?

A

Block the virally encoded H+ channel (M2 protein) and prevent uncoating

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17
Q

How do viruses obtain amantadine and rimantadine resistance?

A

Resistance is common. Mutations in the m2 proton channel

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18
Q

What is the absorption and distribution of amantadine and rimantadine?

A

oral, accumulates in lung. CNS distribution amantadine>rimantadine

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19
Q

How is amantadine eliminated?

A

renal

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20
Q

How is rimantadine eliminated?

A

hepatic

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21
Q

What is the clinical use of amantadine and rimantadine?

A

Prophylactic treatment of flu A but now limited due to resistance

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22
Q

What are the adverse reactions of amatadine?

A

insomnia, difficulty concentrating, dizziness, headache.

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23
Q

What are the adverse reactions of rimatadine?

A

Better than amantadine but poor CNS penetration

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24
Q

What is the mechanism of action of acyclovir?

A

diffuses into the cell where it is triphosphorylated by intracellular kinases. The first phophorylation is done by viral thymidine kinase (allows cell specificity) It then inhibits viral DNA polymerase. Also acts as DNA chain terminator with irreversible binding between DNA polymerase and terminated chain.

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25
Q

How can viruses become resistance to acyclovir?

A

modify thymidine kinase expression is most common. more common in immunosuppressed patient on extended acyclovir treatment.

26
Q

What is the absorption of acyclovir?

A

Poor orally (15-30%), but can be given orally, topically or IV.

27
Q

What is the absorption of valacyclovir?

A

Good orally (80-90%), become acyclovir in the blood.

28
Q

What is the elimination of val/acyclovir?

A

Renal

29
Q

What are the clinical uses of val/acyclovir for primary HSV infection?

A

Beneficial if given within 48-72 hrs. Better if given orally for several days and only has modest benefit if given topically.

30
Q

What are the clinical uses of val/acyclovir for recurrent HSV infection?

A

Given episodically for prodromal symptoms or given chronically for severe recurrent symptoms or risk of transmission is high

31
Q

T or F: Valacyclovir is dosed less frequently than acyclovir?

A

True. Val is qd, acyclovir is bid. Also acyclovir should be given for more days (x5) than val (x1)

32
Q

T or F: Acyclovir can be given for chicken pox.

A

True. Not for children under 12. Qid for 5d for adults with uncomplicated pox. IV tid for 7d for immunosuppressed or severe

33
Q

T or F: VZV is more sensitive to acyclovir than HSV?

A

False, less sensitive and requires doses 2-3x higher

34
Q

T or F: Acyclovir can be given for shingles.

A

TRUE. Can increase rapidity of healing and decrease pain, but best if begun early <72 hrs. Oral acycl 3-5 per day or oral Valacycl bid for 7 days.

35
Q

What are the adverse reactions of acyl/valacycl?

A

Headache, CNS effects with higer dose IV esp for valacycl (confusion, hallucinations, seizures). Renal toxicity with IV but can be dec with hydration. Preg cat B.

36
Q

How is penciclovir given?

A

topically. Don?t really have to know anything about this drug.

37
Q

What is the mechanism of action of docosanol?

A

Prevent the fusion between cellular and viral envelope membranes blocking viral entry into the cell.

38
Q

T or F: Docosanol (abreva) has lots of adverse reactions.

A

False. very well tolerated

39
Q

How is docosanol administered?

A

topically

40
Q

How effective is docosanol?

A

reduces healing time by 0.7 days if begun within 12 hrs of prodromal symptoms.

41
Q

What is the mechanism of action of val/ganciclovir?

A

Phosphorylated by viral kinase UL97 then by host kinases. Incorporates into replicating viral strands slowing DNA elongation

42
Q

What is the most common mechanism of resistance to val/ganciclovir?

A

Mutation in UL97 or in DNA polymerase target.

43
Q

How is ganciclovir absorbed?

A

Poor orally, but can be given orally, intravenously, or intraocularly

44
Q

How is valganciclovir absorbed?

A

Good orally (60% bioavailability)

45
Q

How is foscarnet absorbed?

A

IV only

46
Q

How is cidofovir absorbed?

A

IV only

47
Q

How are val/ganciclovir eliminated?

A

Renal

48
Q

How is foscarnet eliminated?

A

renal

49
Q

How is cidofovir eliminated?

A

renal tubular secretion

50
Q

What can be given with cidofovir to block secretion and decrease nephrotoxicity?

A

probenecid

51
Q

What are the uses of val/ganciclovir?

A

treat CMV retinitis in immunocompromised patients. Prevent CMV with transplants

52
Q

What are the uses of foscarnet?

A

CMV retinitis in patient with HIV

53
Q

What are the uses of cidofovir?

A

CMV retinitis if no response to gancicl or foscar

54
Q

What are the adverse reactions of val/gancicl?

A

Myelosuppression (esp IV route), nausea, diarrhea, fever, rash. Pregnacy cat C.

55
Q

What are the adverse reactions of foscarnet?

A

Renal impairment, CNS abnormalities

56
Q

What are the adverse reactions of cidofovir?

A

dose-dependent proximal tubular nephrotox which can be reduced with prehydration, neutropenia, uveitis

57
Q

What does ribavirin do?

A

Phosphorylated by cellular kinases and inhibits GTP-dependent capping of viral mRNA.

58
Q

What is ribavirin used to treat?

A

HCV and RSV

59
Q

How is ribavirin given?

A

orally with fatty meals

60
Q

How is ribavirin eliminated

A

hepatic metabolism and renal excretion of unchanged drug

61
Q

What are the adverse reactions to ribavirin in RSV?

A

Can cause conjunctival and bronchial irritation. Pregnacy cat X

62
Q

What are the adverse reactions to ribavirin in HCV?

A

hemolytic anemia, cough, pruritis and rash

DD unit 3 (5 decks)

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