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Flashcards in 2 - Systemic Antiviral Agents Deck (99):
1

Once viruses such as human herpes viruses and HIV are acquired, antiviral agents are essentially the sole method of treatment

True

2

The human herpes viruses family includes human herpes virus type 1/HSV-1 and human herpes virus type 2/HSV-2 which most commonly causes herpes labialis and genital herpes respectively, although both types of lesions can be caused by either virus

True

3

HSV-1 and HSV-2 have been shown to cause gingivostomatitis

True

4

HSV-1 and HSV-2 have been shown to cause ocular disease

True

5

HSV-1 and HSV-2 have been shown to cause herpes gladiatorum

True

6

HSV-1 and HSV-2 have been shown to cause eczema herpeticum

True

7

HSV-1 and HSV-2 have been shown to cause herpetic whitlow (paronychia)

True

8

HSV-1 and HSV-2 have been shown to cause neonatal herpes

True

9

HSV-1 and HSV-2 have been shown to cause lumbosacral herpes

True

10

HSV-1 and HSV-2 have been shown to cause herpetic keratoconjunctivitis

True

11

HSV-1 and HSV-2 have been shown to cause herpes encephalitis

True

12

HSV-1 and HSV-2 have been shown to cause cervicitis

True

13

HSV-1 and HSV-2 have been shown to cause erythema multiforme

True

14

Human herpes virus type 3 is also known as varicella-zoster virus (VZV), more commonly called chicken pox in its primary form and shingles/herpes zoster in its recurrent form

True

15

Human herpes type 4 is EBV which causes infectious mononucleosis and Burkitt's lymphoma

True

16

Human herpes virus type 5 is CMV which causes CMV retinitis

True

17

Human herpes virus type 6 causes roseola infantum

True

18

Human herpes virus type 7 causes pityriasis rosea

True

19

Human herpes virus type 8 is Kaposi's sarcoma herpes virus and causes Kaposi's sarcoma

True

20

The 3 primary antiviral drugs with efficacy against HSV-1, HSV-2 and VZV are acyclovir, valacyclovir and famciclovir

True

21

Acyclovir is a guanosine analog

True (valacyclovir is the oral prodrug of acyclovir)

22

Valacyclovir is the oral prodrug of acyclovir

True

23

Activation of acyclovir requires phosphorylation by herpes-specific thymidine kinase prior to bi- and triphosphorylation by host cellular GMP kinase enzymes

True (the active triphosphorylated acyclovir inhibits viral DNA polymerase causing irreversible inhibition of further viral DNA synthesis)
Step 1 = viral thymidine kinase (phosphorylates acyclovir/penciclovir)
Step 2 = human cellular-GMP kinase and other cellular kinases (further phosphorylates acyclovir/penciclovir monophosphate)
Step 3 = acyclovir/penciclovir triphosphate competes with normal deoxyguanosine triphosphate for viral-DNA polymerase
Step 4 = incorporation of acyclovir/penciclovir triphosphate into viral DNA (leads to chain termination and reduced viral replication)

24

Acyclovir does not undergo any hepatic microsomal metabolism

True

25

Acyclovir and Valacyclovir has roughly equal urine and faecal excretion

True(Valacyclovir is the oral prodrug of Acyclovir)

26

Valacyclovir does not undergo any hepatic microsomal metabolism, but is converted to acyclovir

True (acyclovir also does not undergo any hepatic microsomal metabolism)

27

Famciclovir is the oral prodrug of penciclovir

True (just as Valacyclovir is the oral prodrug of acyclovir)

28

Viral thymidine kinase converts the active drug forms acyclovir and penciclovir to acyclovir monophosphate and penciclovir monophosphate which is then acted on by human cellular-GMP kinase and other cellular kinases

True (Valacyclovir is the oral prodrug of acyclovir and Famciclovir is the oral prodrug of penciclovir)
Step 1 = viral thymidine kinase (phosphorylates acyclovir/penciclovir)
Step 2 = human cellular-GMP kinase and other cellular kinases (further phosphorylates acyclovir/penciclovir monophosphate)
Step 3 = acyclovir/penciclovir triphosphate competes with normal deoxyguanosine triphosphate for viral-DNA polymerase
Step 4 = incorporation of acyclovir/penciclovir triphosphate into viral DNA (leads to chain termination and reduced viral replication)

29

Human Cellular-GMP kinases and other cellular kinases covert acyclovir monophosphate or penciclovir monophosphate to either acyclovir triphosphate or penciclovir triphosphate

True
Step 1 = viral thymidine kinase (phosphorylates acyclovir/penciclovir)
Step 2 = human cellular-GMP kinase and other cellular kinases (further phosphorylates acyclovir/penciclovir monophosphate)
Step 3 = acyclovir/penciclovir triphosphate competes with normal deoxyguanosine triphosphate for viral-DNA polymerase
Step 4 = incorporation of acyclovir/penciclovir triphosphate into viral DNA (leads to chain termination and reduced viral replication)

30

Acyclovir triphosphate or penciclovir triphosphate competes with normal deoxyguanosine triphosphate for viral-DNA polymerase

True
Step 1 = viral thymidine kinase (phosphorylates acyclovir/penciclovir)
Step 2 = human cellular-GMP kinase and other cellular kinases (further phosphorylates acyclovir/penciclovir monophosphate)
Step 3 = acyclovir/penciclovir triphosphate competes with normal deoxyguanosine triphosphate for viral-DNA polymerase
Step 4 = incorporation of acyclovir/penciclovir triphosphate into viral DNA (leads to chain termination and reduced viral replication)

31

Acyclovir triphosphate and penciclovir triphosphate are much less inhibitory of human DNA polymerase

True (competes for viral-DNA polymerase)
Step 1 = viral thymidine kinase (phosphorylates acyclovir/penciclovir)
Step 2 = human cellular-GMP kinase and other cellular kinases (further phosphorylates acyclovir/penciclovir monophosphate)
Step 3 = acyclovir/penciclovir triphosphate competes with normal deoxyguanosine triphosphate for viral-DNA polymerase
Step 4 = incorporation of acyclovir/penciclovir triphosphate into viral DNA (leads to chain termination and reduced viral replication)

32

The incorporation of acyclovir triphosphate or penciclovir triphosphate into viral DNAa leads to chain termination with resultant reduced viral replication

True
Step 1 = viral thymidine kinase (phosphorylates acyclovir/penciclovir)
Step 2 = human cellular-GMP kinase and other cellular kinases (further phosphorylates acyclovir/penciclovir monophosphate)
Step 3 = acyclovir/penciclovir triphosphate competes with normal deoxyguanosine triphosphate for viral-DNA polymerase
Step 4 = incorporation of acyclovir/penciclovir triphosphate into viral DNA (leads to chain termination and reduced viral replication)

33

Famciclovir does not undergo any hepatic microsomal metabolism, but is converted to penciclovir

True

34

73% of penciclovir (after conversion from famciclovir) is excreted in the urine, and 27% excreted in the faeces

True (in contrast to roughly equal urine and faecal excretion for acyclovir/Valacyclovir)

35

Oral famciclovir has a higher bioavailability (77%) compared to acyclovir (15-30%) and Valacyclovir (55%)

True
Bioavailability as follows:
Famciclovir > Valacyclovir > Acyclovir

36

Penciclovir triphosphate has a much longer intracellular half life than acyclovir triphosphate

True (Famciclovir is a prodrug that is converted to Penciclovir)
Penciclovir triphosphate = 10-20 hours in HSV-infected cells and 7 hours in VZV-infected cells
Acyclovir triphosphate = <1 hours in HSV and VZV infected cells

37

Acyclovir is FDA approved for primary/first episode of Herpes simplex infection

True
Immunocompetent = 200mg 5 X daily for 10 days (recommended), 400mg TDS for 10 days (real world)
Immunosuppressed = 200-400mg 5 X daily for 10 days, 5mg/kg IV TDS for 7-10 days

38

Acyclovir is FDA approved for recurrent episodes of Herpes simplex infections

True
Immunocompetent = 200mg 5 X daily for 5 days (recommended), 400mg TDS for 5 days (real world)
Immunosuppressed = at least 400mg TDS for 7-10 days

39

Acyclovir is FDA approved for suppressive therapy of Herpes simplex infections

True
Immunocompetent = continuous 400mg BD
Immunosuppressed = at least 400mg BD

40

Acyclovir is FDA approved for primary Varicella zoster infections (chicken pox)

True
Immunocompetent (children) = 20mg/kg QID up to 800mg dose for 5-7 days
Immunocompromised (children) = 10mg/kg IV TDS for 7-10 days

41

Acyclovir is FDA approved for recurrent Varicella zoster infections (herpes zoster/shingles)

True
Immunocompetent = 800mg 5 X daily for 7-10 days
Immunosuppressed = 800mg 5 X daily for 7-10 days

42

Acyclovir is also used in recurrent erythema multiforme (presumed/proven due to HSV)

True
Suppressive therapy = 400mg BD

43

Acyclovir, Valacyclovir and Famciclovir are classified as pregnancy category B

True

44

Acyclovir can be administered topically, orally and intravenously

True

45

Continuous suppressive therapy of genital herpes with acyclovir reduced recurrence by 80-90%, and reduced asymptomatic viral shedding of HSV-2 by 95%

True (400mg BD continuous)

46

Maximal therapeutic benefits of acyclovir in recurrent orofacial HSV infection are seen when therapy is initiated during the prodromal stages prior to vesicle formation

True

47

Acyclovir initiated during orofacial HSV infection outbreak expedites crusting, but does not appear to reduce healing time significantly

True

48

Oral acyclovir suppressive therapy can be used for those with more than 2 orofacial HSV infection annually or a history of ocular HSV disease as this reduces the frequency of HSV labialis and ocular HSV by 50-78%

True (400mg BD continuous)

49

Even though topical acyclovir is promoted for the treatment of orofacial HSV, penetration of the stratum corneum is low and the resulting efficacy is low

True

50

IV acyclovir is reserved for severe illness and in the immunocompromised because of the greater bioavailability

True (disseminated HSV, complicated primary infection, neonatal infection, eczema herpeticum, herpes encephalitis, HSV that fails oral therapy)

51

Acyclovir resistance is low in immunocompetent patients, however HSV-2 resistant isolates are more common in HIV patients

True

52

For efficacious treatment of primary VZV infection (chicken pox), acyclovir must be initiated within the first 24-72 hours after appearance of the characteristic skin eruption

True

53

Acyclovir can shorten the duration of fever and reduce the number of lesions of primary VZV infection (chicken pox), however it's effects on pruritus and onset of new lesions were not consistent

True

54

IV acyclovir is recommended for pregnant women with primary VZV infection (chicken pox) and evidence of pneumonia due to the high Fetal morbidity and mortality

True (no acyclovir related Fetal risk has been documented)

55

Although there has been much controversy regarding the effects of acyclovir on herpes zoster/shingles, acyclovir has been shown to reduce the mean duration of postherpetic neuralgia

True

56

Acyclovir is generally well tolerated regardless of the route of administration (topical, PO or IV) although infrequent adverse effects with PO and IV treatment include nausea, vomiting, diarrhoea and headache

True

57

Infrequent adverse effects with PO acyclovir include nausea, vomiting, diarrhoea and headache

True

58

Infrequent adverse effects with IV acyclovir include nausea, vomiting, diarrhoea, headache, infusion-associated phlebitis and infusion site inflammation in addition to reversible renal impairment due to crystalline nephropathy

True

59

Infrequent adverse effects with IV acyclovir include infusion-associated phlebitis

True

60

Infrequent adverse effects with IV acyclovir include infusion site inflammation

True

61

Infrequent adverse effects with IV acyclovir include reversible renal impairment due to crystalline nephropathy

True

62

Probenecid may increase the serum level and bioavailability of acyclovir due to reduced renal clearance from decreased renal tubular secretion

True

63

Zidovudine (nucleoside reverse transcriptase inhibitor) may increase the serum level of acyclovir and cause severe drowsiness and lethargy

True

64

Valacyclovir has a 3-5 times greater bioavailability than oral acyclovir, and nearly as potent as IV acyclovir

True
Bioavailability as follows:
Famciclovir > Valacyclovir > Acyclovir

65

Valacyclovir is FDA approved for primary/first episode of Herpes simplex infection

True
Immunocompetent = 1000mg BD for 10 days
Immunocompromised = no studies reported (acyclovir used instead)

66

Valacyclovir is FDA approved for recurrent episodes of Herpes simplex infections

True
Immunocompetent = 500mg BD for 3 days, 2000mg BD for 1 day (if given during prodromal stage for recurrent orofacial HSV)
Immunosuppressed = 500mg BD for 7 days
Recurrent orofacial HSV Prophylaxis prior to laser cutaneous resurfacing = 500mg BD to be started 1 day prior for 10-14 days

67

Valacyclovir is FDA approved for suppressive therapy of Herpes simplex infections

True
Immunocompetent = 500mg daily continuous, 1000mg daily continuous if 10 or more HSV recurrences each year
Immunosuppressed = 500mg BD continuous

68

Valacyclovir is FDA approved for recurrent Varicella zoster infections (herpes zoster/shingles)

True
Immunocompetent = 1000mg TDS for 7 days
Immunocompromised = 1000mg TDS for 7-10 days

69

Valacyclovir is also used in recurrent erythema multiforme (presumed/proven due to HSV)

True

70

In immunocompromised patients subsequent upon solid organ or bone marrow transplantation, Valacyclovir 2000mg QID is also an effective prophylactic strategy against CMV infection

True

71

Valacyclovir is more efficacious than acyclovir in ameliorating postherpetic neuralgia

True

72

The more convenient dosing schedule (BD vs 5X daily) and the quicker cessation of pain makes Valacyclovir more efficacious than acyclovir in treating herpes zoster/shingles

True

73

Adverse effects of Valacyclovir include nausea and headaches

True (similar to acyclovir)

74

Cimetidine may reduce the rate of conversion of Valacyclovir to acyclovir, but does not affect the extent of this conversion

True (even though cimetidine is a CYP P450 inhibitor, unknown mechanism as Valacyclovir does not rely on hepatic microsomal metabolism)

75

Probenecid may reduce the rate of conversion of Valacyclovir to acyclovir, but does not affect the extent of this conversion

True (probenecid reduces renal tubular secretion)
NB. Equal excretion of Valacyclovir in urine and faeces

76

Famciclovir is FDA approved for primary/first episode of Herpes simplex infection

True
Immunocompetent = 250mg TDS for 10 days
Immunocompromised = no studies reported (acyclovir used instead)

77

Famciclovir is FDA approved for recurrent episodes of Herpes simplex infections

True
Immunocompetent (recurrent genital HSV) = 125mg BD for 5 days, 1000mg BD for 1 day (similar safety and efficacy)
Immunocompetent (recurrent orofacial HSV) = single 1500mg dose (given at earliest onset of symptoms), 250mg/500mg TDS for 5 days (early treatment of UV-induced recurrences with higher dose recommended for patients with history of frequency recurrences)
Immunocompromised = 500mg for 7 days

78

Famciclovir is FDA approved for suppressive therapy of Herpes simplex infections

True
Immunocompetent = 250mg BD continuous
Immunocompromised = 500mg BD continuous

79

Famciclovir is FDA approved for recurrent Varicella zoster infections (herpes zoster/shingles)

True
Immunocompetent = 500mg TDS for 7 days
Immunocompromised = 500mg TDS for 7-10 days

80

Famciclovir is not used in recurrent erythema multiforme (presumed/proven due to HSV)

True (acyclovir and Valacyclovir used instead)

81

There are no differences in safety or efficacy between Famciclovir and Valacyclovir in the treatment of herpes zoster/shingles

True

82

Famciclovir is equally safe and effective as acyclovir for ophthalmic herpes zoster/shingles, but Famciclovir is more convenient with its TDS dosing

True (acyclovir is 5 X daily dosing)

83

Famciclovir is an efficacious oral agent that can be used as an alternative to IV acyclovir in immunocompromised patients with recurrent Varicella zoster infections (herpes zoster/shingles), however patients must be monitored closely and started on IV acyclovir if they develop any signs and symptoms of disseminated disease

True

84

The role of Famciclovir in primary VZV infection (chicken pox) has not been well evaluated

True

85

Adverse effects of Famciclovir include nausea, diarrhoea and headaches

True

86

Cimetidine may increase the serum levels of Famciclovir/penciclovir (no clinical importance)

True

87

Theophylline may increase the serum levels of Famciclovir/penciclovir due to reduction of penciclovir renal clearance (no clinical importance)

True

88

Famciclovir may increase the serum level of digoxin due to an uncertain mechanism

True

89

In general, acyclovir, Valacyclovir and Famciclovir are equivalent in their safety and efficacy for HSV infections

True (however Valacyclovir and Famciclovir are more effective in reducing the duration of shingles/zoster-associated pain than acyclovir due to their superior bioavailability)

90

Valacyclovir and Famciclovir are more effective in reducing the duration of shingles/zoster-associated pain than acyclovir due to their superior bioavailability

True (hence Valacyclovir and Famciclovir is generally preferred for shingles/zoster infections, and considered equivalent for HSV and VZV infections)

91

Valacyclovir and Famciclovir are considered overall equivalent for therapy of HSV and VZV infections

True (acyclovir also still has a significant role in HSV infections, but inferior to Valacyclovir and Famciclovir for VZV associated pain) - acyclovir is less effective against VZV due to less efficient phosphorylation by the VZV viral thymidine kinase

92

Acyclovir still has a significant role in HSV infections with equal safety and efficacy to Valacyclovir and Famciclovir, but is inferior to Valacyclovir and Famciclovir for VZV infections associated pain duration

True

93

The following are reasons to offer suppression vs episode therapy of recurrent genital HSV or HSV labialis:
(1) 6 or more outbreaks a year
(2) severity of outbreaks due to physical or emotional stressors
(3) lack of sufficient prodrome such that episodic therapy would have little benefit
(4) sexual partner who is seronegative for HSV (especially HSV-2) to avoid asymptomatic viral shedding and transmission

True

94

Immunocompromised patients include:
(1) HIV patients
(2) patients on systemic immunosuppressive drugs
(3) patients with internal malignancies

True

95

Frequent use of acyclovir for the treatment and suppression of HSV infections has led to the emergence of acyclovir-resistant HSV strains, and may be cross-resistant to Valacyclovir and Famciclovir

True (patients who fail standard therapy with PO or IV acyclovir can be managed with IV foscarnet or cidofovir, including topical cidofovir)

96

Resistance to acyclovir most frequently results from mutations in the viral thymidine kinase gene

True (and less frequently mutations in viral DNA polymerase)

97

Foscarnet and cidofovir are 2 IV antiviral therapies which are more toxic than acyclovir and are not recommended as first-line HSV treatment as both work through inhibition of viral DNA polymerase directly and do not rely on phosphorylation and activation of the drug by thymidine kinase (unlike acyclovir, Valacyclovir and Famciclovir)

True (acyclovir and penciclovir triphosphate inhibit viral DNA polymerase but acyclovir and penciclovir are first phosphorylated by thymidine kinase and human cellular-GMP kinases)

98

In the first line therapy of HSV infection there is little basis to recommend either acyclovir, Valacyclovir or Famciclovir over any other, except for the greater convenience in the dosing frequency of Valacyclovir and Famciclovir

True

99

HSV vaccines prevents acquisition of HSV-2 infection in patients seronegative for HSV-1 or HSV-2; although the vaccine gives no protection to patients who are HSV-1 seropositive

True