2 - Systemic Antiparasitic Agents Flashcards Preview

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

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

A

True

2
Q

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

A

True

3
Q

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

A

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

4
Q

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

A

True (ivermectin alone often fails in crusted scabies)

5
Q

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

A

True (ivermectin alone fails in crusted scabies)

6
Q

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

A

True (ivermectin is a substrate of CYP3A4)

7
Q

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

A

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

8
Q

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

A

True

9
Q

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

A

True

10
Q

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

A

True (scabies is not FDA approved)

11
Q

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

A

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
Q

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

A

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

13
Q

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

A

True

14
Q

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

A

True

15
Q

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

A

True

16
Q

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

A

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
Q

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

A

True (less common in the setting of scabies)

18
Q

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

A

True (less common in the setting of scabies)

19
Q

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

A

True (less common in the setting of scabies)

20
Q

Tachycardia is an infrequent adverse reaction to Ivermectin

A

True

21
Q

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

A

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

22
Q

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

A

True

23
Q

Facial oedema is an infrequent adverse reaction to Ivermectin

A

True

24
Q

Orthostatic hypotension is an infrequent adverse reaction to Ivermectin

A

True

25
Q

Diarrhoea is an infrequent adverse reaction to Ivermectin

A

True

26
Q

Nausea is an infrequent adverse reaction to Ivermectin

A

True

27
Q

CNS symptoms is a rare adverse reaction to Ivermectin

A

True

28
Q

SJS is a rare adverse reaction to Ivermectin

A

True

29
Q

Abnormal LFTs is a rare adverse reaction to Ivermectin

A

True

30
Q

Ivermectin may enhance the anticoagulant effect of warfarin

A

True

31
Q

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

A

True

32
Q

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

A

True

33
Q

Ivermectin is not recommended during lactation

A

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

34
Q

Ivermectin is not recommended for children under 15kg

A

True

35
Q

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

A

True

36
Q

Albendazole has both antihelminthic and antiprotozoal activity

A

True

37
Q

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

A

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

38
Q

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

A

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
Q

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

A

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

40
Q

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

A

True

41
Q

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

A

True

42
Q

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

A

True

43
Q

Ivermectin is significantly more effective than Albendazole for pediculosis

A

True

44
Q

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

A

True

45
Q

Albendazole may cause bone marrow suppression with aplastic anaemia and agranulocytosis

A

True

46
Q

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

A

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

47
Q

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

A

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

48
Q

Other adverse effects of Albendazole include hepatotoxicity

A

True

49
Q

Other adverse effects of Albendazole include GI discomfort

A

True

50
Q

Other adverse effects of Albendazole include diarrhoea

A

True

51
Q

Other adverse effects of Albendazole include headache

A

True

52
Q

Other adverse effects of Albendazole include dizziness

A

True

53
Q

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

A

True

54
Q

Albendazole is a CYP1A2 inhibitor

A

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

55
Q

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

A

True (pregnancy test should be obtained before starting therapy)

56
Q

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

A

True

57
Q

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

A

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
Q

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

A

True

59
Q

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

A

True

60
Q

Thiabendazole is indicated for the treatment of strongyloidiasis

A

True

61
Q

Thiabendazole is indicated for the treatment of cutaneous larva migrans

A

True

62
Q

Thiabendazole is indicated for the treatment of visceral larva migrans

A

True

63
Q

Thiabendazole has been used for the treatment of intestinal roundworms infestation

A

True

64
Q

Thiabendazole has been associated with hepatotoxicity

A

True

65
Q

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

A

True

66
Q

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

A

True

67
Q

Thiabendazole has been associated with SJS

A

True

68
Q

Thiabendazole is a CYP1A2 inhibitor

A

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

69
Q

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

A

True

70
Q

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

A

True