2 - Systemic Antiparasitic Agents Flashcards Preview

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Flashcards in 2 - Systemic Antiparasitic Agents Deck (70):
1

Ivermectin is a semisynthetic antihelminthic derived from fermentation products of Streptomyces avermitilis

True

2

Ivermectin has structural similarity to that of macrolide antibacterial agents (erythromycin, clarithromycin, azithromycin)

True

3

Although topical permethrin appears to be the most effective treatment for scabies, ivermectin appears to be an effective oral agent

True (data considering both cost and efficacy suggests that benzyl benzoate and ivermectin are most cost-effective for the treatment of scabies)

4

In patients with crusted scabies, the response to oral ivermectin is variable and oral therapy in combination with topical scabicides and keratolytics are advocated

True (ivermectin alone often fails in crusted scabies)

5

Ivermectin appears comparable or slightly inferior to permethrin in efficacy against non-crusted scabies, but has the convenience of oral dosing

True (ivermectin alone fails in crusted scabies)

6

Ivermectin is primarily metabolised by CYP3A4 in the liver and excreted in the faeces

True (ivermectin is a substrate of CYP3A4)

7

As <1% of the administered ivermectin dose is excreted in the urine (mainly faecal excretion), dose adjustment is needed with biliary obstruction but renal failure is not likely to affect metabolism

True (metabolised by the liver and excreted in the faeces)

8

Bioavailability of ivermectin is increased when the drug is administered with a high-fat meal

True

9

Ivermectin selectively binds to glutamate-gated chloride ion channels found in invertebrate (parasites) nerve and muscle cells, resulting in increased permeability of cell membranes to chloride ions and hyperpolarisation of the nerve/muscle cell causing death of the parasite

True

10

Ivermectin is FDA approved in the treatment of intestinal strongyloides specifically caused by Strongyloides stercoralis, and onchocerciasis (river blindness) caused by Onchocerca volvulus

True (scabies is not FDA approved)

11

Ivermectin is most widely used in dermatology (off label) for the treatment of scabies

True (200 ug/kg as a single dose, then repeated in 7-10 days) - addition of topical keratolytics and topical permethrin in crusted scabies

12

Ivermectin is used in dermatology (off label) to some extent for the treatment of pediculosis (lice)

True (400 ug/kg as a single dose on Day 1 and Day 8)

13

Ivermectin is used in dermatology (off label) to some extent for the treatment of cutaneous larva migrans

True

14

A single dose of Ivermectin has also been used empirically (off label) to reduce the pruritus in homeless populations

True

15

Ivermectin has been used in the control of hospital and institutional outbreaks of scabies, and may be superior to topical treatment in the setting of mass infestation

True

16

Ivermectin is commonly associated with Mazzoti-type reactions (oedema, urticarial rash, systemic symptoms and ophthalmological reactions) when used in the treatment of helminthic infestations

True (less common in the setting of scabies)
NB. Mazzoti reactions may be due to allergic and inflammatory responses to the death of microfilariae or to microorganisms within the worms

17

Ivermectin is commonly associated with pruritus in the setting on helminthic infestation

True (less common in the setting of scabies)

18

Ivermectin is commonly associated with fever in the setting of helminthic infestation

True (less common in the setting of scabies)

19

Ivermectin is commonly associated with lymphadenopathy or lymph node tenderness in the setting of helminthic infestation

True (less common in the setting of scabies)

20

Tachycardia is an infrequent adverse reaction to Ivermectin

True

21

The Mazzoti reactions commonly associated with ivermectin in patients with onchocerciasis may be due to allergic and inflammatory responses to the death of microfilariae or to microorganisms within the worms

True (doxycycline can eliminate endosymbiotic bacteria within filarial worms, and reducing the incidence of Mazzoti reactions)

22

Doxycycline can eliminate endosymbiotic bacteria within filarial worms, and reducing the incidence of Mazzoti reactions in patients with onchocerciasis associated with ivermectin treatment

True

23

Facial oedema is an infrequent adverse reaction to Ivermectin

True

24

Orthostatic hypotension is an infrequent adverse reaction to Ivermectin

True

25

Diarrhoea is an infrequent adverse reaction to Ivermectin

True

26

Nausea is an infrequent adverse reaction to Ivermectin

True

27

CNS symptoms is a rare adverse reaction to Ivermectin

True

28

SJS is a rare adverse reaction to Ivermectin

True

29

Abnormal LFTs is a rare adverse reaction to Ivermectin

True

30

Ivermectin may enhance the anticoagulant effect of warfarin

True

31

Australia has shown increasing increasing resistance to both topical permethrin and oral ivermectin in the treatment of scabies due to increased drug metabolism and efflux mechanisms

True

32

Ivermectin is classified as pregnancy category C and teratogenic effects have been observed in animal studies

True

33

Ivermectin is not recommended during lactation

True (enters breast milk, and safety and efficacy for use in children <15kg have not been established)

34

Ivermectin is not recommended for children under 15kg

True

35

Mass infestations of scabies are the best setting for the use of ivermectin

True

36

Albendazole has both antihelminthic and antiprotozoal activity

True

37

Albendazole has low aqueous solubility and so is poorly absorbed from the GI tract

True (oral bioavailability is enhanced when Albendazole is taken with a fatty meal)

38

The systemic antihelminthic activity of Albendazole is attributed to its primary metabolite Albendazole sulfoxide

True (Albendazole is rapidly converted to the sulfoxide metabolite before reaching the systemic circulation, such that the plasma levels of Albendazole as the parent drug is negligible in plasma)

39

Biliary elimination is the major route of excretion for Albendazole and its metabolite Albendazole sulfoxide, with <1% excreted in the urine

True (biliary obstruction will affect blood levels, but renal failure is unlikely to affect levels)

40

Albendazole sulfoxide (major metabolite of Albendazole) is mainly bound to plasma protein and achieves excellent distribution throughout the body

True

41

Albendazole inhibits tubulin polymerisation, which causes immobilisation and death of the susceptible organisms

True

42

Albendazole is FDA approved for the treatment of neurocystocercosis and hydatid disease (tapeworms)

True

43

Ivermectin is significantly more effective than Albendazole for pediculosis

True

44

Albendazole has not been adequately studied in children under 1 year of age

True

45

Albendazole may cause bone marrow suppression with aplastic anaemia and agranulocytosis

True

46

Bone toxicity may occur in patients on Albendazole with and without underlying hepatic dysfunction and FBC should be monitored

True (biliary obstruction affects blood levels as the drug is mainly excreted in the bile)

47

Patients with liver disease on Albendazole appear to be at an increased risk for bone marrow suppression

True (biliary obstruction affects blood levels as the drug is mainly excreted in the bile)

48

Other adverse effects of Albendazole include hepatotoxicity

True

49

Other adverse effects of Albendazole include GI discomfort

True

50

Other adverse effects of Albendazole include diarrhoea

True

51

Other adverse effects of Albendazole include headache

True

52

Other adverse effects of Albendazole include dizziness

True

53

Hypersensitivity reactions presenting with rash, pruritus or urticaria is rarely associated with Albendazole

True

54

Albendazole is a CYP1A2 inhibitor

True (may inhibit theophylline metabolism as theophylline is a CYP1A2 substrate)

55

Albendazole is classified as pregnancy category C as it is both teratogenic and embryotoxic in animal studies

True (pregnancy test should be obtained before starting therapy)

56

Thiabendazole is a broad spectrum antihelminthic that has been used for the treatment of parasitic infestations in humans and animals

True

57

Thiabendazole is metabolised almost entirely by the liver and the metabolites are substantially excreted by the kidneys

True (therefore the drug should be used with caution and the dose may need to be adjusted in patients with impaired hepatic or renal function)

58

Thiabendazole is rapidly absorbed and metabolised almost completely to its 5-hydroxy form in the liver

True

59

The mechanism of action of thiabendazole is unknown but it may inhibit the helminth-specific fumarate reductase

True

60

Thiabendazole is indicated for the treatment of strongyloidiasis

True

61

Thiabendazole is indicated for the treatment of cutaneous larva migrans

True

62

Thiabendazole is indicated for the treatment of visceral larva migrans

True

63

Thiabendazole has been used for the treatment of intestinal roundworms infestation

True

64

Thiabendazole has been associated with hepatotoxicity

True

65

Thiabendazole has been associated with anorexia and abdominal symptoms such as nausea, vomiting, diarrhoea, and abdominal pain

True

66

Thiabendazole has been associated with CNS symptoms such as convulsions, confusion, tinnitus and depression

True

67

Thiabendazole has been associated with SJS

True

68

Thiabendazole is a CYP1A2 inhibitor

True (may increase theophylline and caffeine levels as these 2 are CYP1A2 substrates)

69

Thiabendazole is classified as pregnancy category C as birth defects have been observed in animal studies

True

70

Ivermectin may rarely cause potentially fatal encephalopathy in patients co-infected with loiasis

True