Antiparasitic agents Flashcards

1
Q

What are the three common targets of antiparasitic chemotherapy?

A
  1. Enzymes or processes found only in the parasite
  2. Enzymes/processes found in both us and parasite, but only indispensable in the parasite
  3. Common biochemical functions but with different pharmacological properties
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2
Q

What is an example of a process that is found in both us and parasite, but indispensable in the parasite?

A

Purine salvage pathway

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3
Q

What are the three major intestinal protozoans that we have treatments for?

A

Giardia
Amebiasis
Trichomoniasis

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4
Q

What are the two different forms of entamoeba histolytica? What does this cause?

A

Trophozoite and cysts

Dysentery, brain lesions

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5
Q

What are the two different forms of giardiasis? What does this cause?

A

Trophozoite and cysts

Dysentery

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6
Q

What are the two forms of trichomoniasis? What does this cause?

A

Trophozoite

metronidazole

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7
Q

What is the drug used to treat giardia?

A

metronidazole

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8
Q

What is the drug used to treat Amebiasis?

A

metronidazole

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9
Q

What is the drugs that is used to treat trichomoniasis?

A

metronidazole

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10
Q

What is the MOA of metronidazole?

A

Generates ROS that damages DNA

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11
Q

What is the parasitic enzyme parasites have, that converts metronidazole to its active form?

A

PFOR (pyruvate;ferredoxin oxidoreductase)

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12
Q

What is the route for metronidazole? Is it well absorbed?

A

Oral

Well absorbed

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13
Q

What are the side effects of metronidazole?

A

HA
Dry mouth
n/v/d

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14
Q

What should pts avoid taking with metronidazole? Why?

A

EtOH

Has a disulfiram like effect

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15
Q

Who should be treated with trich infection?

A

Sexual parters

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16
Q

How effective is metronidazole in the treatment of amebiasis?

A

Good at killing trophozoites, but need to use something else to kill the cysts

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17
Q

Is resistance a problem with metronidazole?

A

Not really, but trich has increased levels

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18
Q

How is resistance to metronidazole effected?

A

Increased in the activity of other oxidoreductase

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19
Q

What are the two drugs that are used to f/u treatment for amebiasis with metronidazole?

A

Iodoquinol
or
paromomycin

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20
Q

What is the MOA of iodoquinol? What is it used to treat? What is significant about its absorption?

A

unknown

f/u treatment for amebiasis (entamoeba histolytica) to get rid of GUT cysts/trophozoites

Poor absorption, so stays in GI tract lumen

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21
Q

What are the adverse effects of iodoquinol?

A

GI discomfort

Optic atrophy in children

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22
Q

What is paromomycin used to treat? MOA?

A

Entamoeba histolytica

Aminoglycoside–Inhibits protein synthesis

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23
Q

Is paromomycin effective against trophozoites that have infected other tissues besides the gut?

A

No

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24
Q

Which is more toxic, paromomycin or iodoquinol?

A

Iodoquinol

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25
Q

What is cryptosporidium parvum? What dz does it cause? In whom is it usually symptomatic?

A

Water borne parasite that causes profuse watery diarrhea

Immunocompromised

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26
Q

What is the treatment for cryptosporidium parvum?

A

Nitazoxanide

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27
Q

What is the MOA of nitazoxanide?

A

interferes with ferredoxin oxidoreductase (PFOR) (disrupts energy metabolism in the parasite)

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28
Q

How is nitazoxanide administered? Is there resistance against this?

A

Orally

No resistance

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29
Q

What is nitazoxanide used to treat?

A

Cryptosporidium parvum

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30
Q

What is the treatment for pneumocystis-jirovecii?

A

trimethoprim-Sulfamethoxazole

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31
Q

What is the treatment for toxoplasma gondii?

A

Pyrimethamine-sulfadiazine

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32
Q

What is the MOA of sulfonamides?

A

PABA analogs that inhibit the production of pteroic acid from PABA by the enzyme dihydropteroate synthase

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33
Q

What is the MOA of diaminopyrimidines?

A

Inhibitors of the enzyme DHFR

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34
Q

What are adverse reactions with sulfa drugs?

A

Rash

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35
Q

What is the basis for selective toxicity with diaminopyrimidines?

A

parasite DHFR is inhibited at considerably lower concentrations

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36
Q

What is the major adverse effects of pyrimethamine-sulfa?

A

Hematological abnormalities

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37
Q

What is administered with pyrimethamine-sulfadiazine to prevent folate toxicity?

A

Leucovorin

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38
Q

Does pyrimethamine-sulfadiazine affect the dormant tissue cysts of toxoplasma?

A

No

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39
Q

Is there resistance to TMP-SMX in T-Gondii? P.Jirovecii?

A

Yes

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40
Q

What are the two forms of malaria that can hide out in the liver?

A

Vivax and ovale

41
Q

What are the five drugs that are used to treat malaria (not the liver form of vivax and ovale)?

A
Chloroquine
quinine
mefloquine
Malarone
Artminisine
42
Q

What is the only antimalarial that can kill off the liver parts of vivax/ovale?

A

Primaquine

43
Q

What is the MOA of chloroquine?

A

Unclear, thought to interfere with parasites ability to detoxify compounds

44
Q

What are the side effects of chloroquine?

A

HA
n/v
Dizziness/confusion
Blurred vision

45
Q

What stages of malaria does chloroquine kill?

A

All asexual stages of plasmodium

46
Q

Which of the antimalarials has a large resistance? Where in the world is it still effective?

A

Chloroquine– Everywhere but west of the panama canal

47
Q

What is the MOA of quinue?

A

Hb degradation, may complex with parasite DNA

48
Q

Which antimalarial has the poorest therapeutic:toxic ratio of all?

A

Quinine

49
Q

What are the side effects of Quinine?

A

Cinchonism

Hypoglycemia (quine induces release of insulin)

50
Q

What causes the hypoglycemia with Quinine administration?

A

Release of parasites in the blood stream

51
Q

What stages of the malaria life cycle does quine affect?

A

All aexual species

52
Q

What is the MOA of mefloquine?

A

Hb degradation, may complex with parasite DNA

53
Q

What are the odd, adverse side effects of mefloquine?

A

Neuropsychiatric

54
Q

Is mefloquine used for prophylaxis? Is it well tolerated?

A

Yes, and yes

55
Q

How does the treatment dose of mefloquine compare to the prophylactic dose?

A

3-5x greater

56
Q

What is the spectrum of mefloquine? Resistance?

A

Effective against all species of plasmodium

57
Q

What is the only drug that can get rid of the liver forms of vivax and ovale?

A

Primaquine

58
Q

What is the MOA of primaquine?

A

Interfere with mitochondrial ETC

59
Q

What is the major toxicity with primaquine?

A

RBC lysis with G6PD deficiency

60
Q

What disease can have a hemolytic anemia with antimalarials?

A

G6PD deficiency

61
Q

What is the spectrum of use for primaquine? Resistance?

A

vivax and ovale

There are some emerging resistance

62
Q

What two drugs comprise malarone? What type of malaria is this effective against? Is there resistance against this?

A

Atovaquone + proguanil

p. falciparum malaria

No resistance yet

63
Q

What is the MOA of atovaquone? Spectrum? How well is it absorbed? How well is it tolerated?

A

MOA ?
Poorly absorbed
Effective against plasmodium
well tolerated

64
Q

What is the MOA of proguanil?

A

Inhibits dihydrofolate reductase (DHFR)

65
Q

Why is proguanil rarely used alone?

A

Development of resistance

66
Q

What is the MOA of doxycycline in malaria treatment?

A

Thought to inhibit the growth of plasmodium by disrupting protein synthesis

67
Q

What are the major side effect of doxycycline?

A

Photosensitivity dermatitis

staining of teeth

68
Q

What is the spectrum and resistance of doxycycline? Resistance?

A

Effective against all species of plasmodium

Little evidence of resistance

69
Q

What is the MOA of artemisinin?

A

Interacts with Fe, ROS generation ?

70
Q

What are the side effects of artemisinin?

A

n/d

71
Q

What is the spectrum of artemisinin? Resistance?

A

Effective against all malaria, but falciparum has resistant strains

72
Q

What are the 5 intestinal nematode infections?

A
Enterobius vermicularis
Ascaris lumbricoides
Necator americanus
Trichuris trichiura
Strongyloides stercoralis
73
Q

What are the 2 general MOAs of anthelminthics?

A

Inhibit mitosis in the parasite

Causes muscle paralysis of the parasite

74
Q

What are the three benzimidazoles?

A

Albendazole
Mebendazole
Thiabendazole

75
Q

Why is it that it’s alright that there is little gut absorption of benzimidazoles?

A

Treating worms in the intestines

76
Q

Do you want to take benzimidazole on an empty stomach? Why or why not?

A

Yes, to cause greatest effect against parasite

77
Q

Why are benzimidazoles contraindicated in prego?

A

inhibit mitosis

78
Q

What are the side effect of benzimidazoles?

A

GI

CNS disturbances

79
Q

What is the spectrum of albendazole/mebendazole?

A

Pinworms, hookworms, whipworms, ascariasis

80
Q

What is the spectrum of thiabendazole? (2)

A

Strongyloides

Cutaneous larval migrans

81
Q

What is the treatment of choice for strongyloides?

A

Thiabendazole

82
Q

What is the treatment for cutaneous larval migrans?

A

Thiabendazole

83
Q

What causes cutaneous larval migrans?

A

Ancylostoma duodenale

84
Q

What is the MOA of Ivermectin?

A

Causes hyperpolarization in muscles cells, resulting in paralysis of parasite, with NO effect on mammal cells

85
Q

What is ivermectin used to treat?

A

Intestinal and extraintestinal infections of:

  • Strongyloides
  • loa loa
  • O.volvulus (river blindness)
  • Wuchereria bancrofti (filariasis)
86
Q

What is the advantage of using ivermectin in treatment of parasites?

A

Can penetrate into tissues

87
Q

What is the treatment for river blindness?

A

Ivermectin

88
Q

Is there resistance with ivermectin?

A

No evidence

89
Q

What is the cause of river blindness?

A

O Volvulus

90
Q

What disease does Wuchereria bancrofti cause?

A

Filariasis

91
Q

What disease does B. Malayi cause?

A

Lymphatic Filariasis

92
Q

What is the MOA of pyrantel pamoate?

A

Activates cholinergic nicotinic receptors in the somatic muscles of nematodes and thereby produces a depolarizing neuromuscular blockade

93
Q

What is the drug of choice for pinworm?

A

Pyrantel pamoate

94
Q

What are the side effects of pyrantel pamoate?

A

Well tolerated, but mild GI disturbances

95
Q

What is the treatment of choice for tapeworms and fluke?

A

Praziquantel

96
Q

What are the diseases that praziquantel used to treat?

A

tapeworm and flukes

97
Q

What is the MOA of praziquantel?

A

Increases the Ca permeability of the worm’s tegument, causing its depolarization

98
Q

Is praziquantel well absorbed? Tolerated? What are the side effects?

A

Well absorbed and tolerate

HA, dizziness

99
Q

What is the treatment for Cysticercosis?

A

Praziquantel