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GI Final > Fitzpatrick: Parasitic, protozoa, C diff Pharm > Flashcards

Fitzpatrick: Parasitic, protozoa, C diff Pharm Flashcards

1
Q

What drugs are used for nematodes?

A 
Albendazole
Mebendazole
Pyrantel pamoate
Diethylcarbamazine
Ivermectin
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2
Q

What drugs are used for Cestodes (tapeworms)?

A

Albendazole
Mebendazole
Praziquantel
Niclosamide

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3
Q

What drugs are used for Trematodes?

A

Praziquantel

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4
Q

What are the soil-transmitted helminths?

A

Ascaris
hookworm
trichuris

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5
Q

What is used to treat these nematodes in endemic areas?

A

Albendazole

  • Mebendazole is older
  • these are both benzimidazoles
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6
Q

MOA of benzimidazoles (Albendazole and mebendazole and Thiabendazole)

A
  • they disrupt microtubule dynamics
  • bind to parasite B-tubulin, disrupt microtubule polymerization and microtubule-dependent processes
  • remember that microtubules are made from alpha and beta tubulin dimers…
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7
Q

Where are nematodes usually residing?

A

the intestinal tract

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8
Q

Why is mebendazole so great?

A

poor absorption, plus efficient metabolism, plus protein binding= LOW SYSTEMIC EXPOSURE
-so, it’s safe and effective :)

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9
Q

How is Albendazole bioavailability and distribution?

A

modest absorption+EFFICIENT METABOLISM = low systemic exposure to parent drug
-safe and effects as a single dose

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10
Q

Does albendazole itself have a lot of systemic exposure?

A

no, negligible

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11
Q

What does abendazole get metabolized to that gets distributed a lot more places to kill tissue dwelling helminths, hydatid cysts?

A

Albendazole to Albendazole sulfoxide

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12
Q

What does albendazole sulfoxide get metabolized to and what happens to it?

A

Albendazole sulfone

  • inactive metabolite
  • renal clearance
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13
Q

Why is Thiabendazole only good for cutaneous use?

A

it has high systemic toxicity

-it’s good for larval migrans apparently

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14
Q

Which anti-helminthic drug should be used for Enterobius vermicularis (pinworm)?

A

Mebendazole

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15
Q

Which anti-helminthic drug should be used for Ancylostoma duodenale (Hookworm)?

A

Albendazole

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16
Q

Ascaris lubricpoides?

A

Albendazole and Mebendazole

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17
Q

Trichuris trichiura (whipworm)?

A
  • Mebendazole
  • Albendazole
  • 3 day course most effective
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18
Q

Toxocara spp

Larval migrans

A

Albendazole

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19
Q

Why are we scared of albendazole and mebendazole in preggo people?

A

They are embryotoxic and teratogenic in preggo rats

-Pregnancy category C, not recommended in humans

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20
Q

What is an alternative or adjunctive nematode therapy that is effective against hookworm, pinworm, and roundworm but INEFFECTIVE AGAINST TRICHURIS TRICHIURA?

A

Pyrantel pamoate

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21
Q

What is in the NM junction of nematodes

A

N-AChR

-so they use acetylcholine a lot

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22
Q

What is Pyrantel

A

a depolarizing NM blocking agent

-causes persistent activation of nicotinic acetylcholine receptors (N-AChR) and spastic paralysis of the worm

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23
Q

What should we consider when we give pyrantel?

A

Worm burden

-they can get into places we don’t want them to be and clog up the joint

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24
Q

What is the active ingredient in Pyrantel Pamoate?

A
  • Pyrantel

- Pamoate is just the chewable component

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25
Q

Pyrantel’s bioavailability

A

Poorly absorbed from the GI tract

  • confines its action to intralumenal GI nematodes
  • less than 15% excreted in urine as parent drug and metabolite
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26
Q

What ppl do we use Pyrantel with caution?

A

Pregnant women and children <2

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27
Q

What was the other NEmatode/Helminth therapy we talked about?

A

Ivermectin

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28
Q

What is Ivermectin used for?

A

intestinal strongloidyiasis- thread worm
and
Onchocerciasis- River Blindness

29
Q

What does Ivermectin do?

A

Activates Glutamate-Gated Chloride Channels

  • causes Cl-current
  • hyperpolarization
  • paralysis
30
Q

Can Ivermectin cross the BBB?

A

no

-so it won’t mess with our GABA gated CL channels

31
Q

So, when is Ivermectin usually contraindicated?

A

When the Blood brain barrier is disrupted (meningitis, Trypanosomiasis)

32
Q

What has been the most extensive use for ivermectin in humans?

A

Onchoceriasis (River blindness) control in Africa

  • also useful for lymphatic Filariasis
  • Wuchereria bancrofti
  • Brugia malayi
33
Q

What is Diethylcarbamazine used for?

A
  • Lymphatic filariasis

- Loasis

34
Q

What is bad about Diethylcarbamazine?

A

significant toxicity due to host-response following death of parasites

35
Q

What are the Cestodes that we have to worry about?

A

Cysticercosis
Echinococcosis
Taeniasis
Diphyllobrothriasis

36
Q

When are people in an infective stage with Cysticercosis?

A

When they have EGGS in their stool

37
Q

When are people in the Diagnostic stage of cysticercosis?

A

When there are gravid proglottids in the feces

38
Q

What is the drug of choice for all adult form tapeworm infection?

A

Praziquantel

39
Q

What drug is used elsewhere but not in the US for tapeworm infections?

A

Niclosamide

40
Q

What is the drug of choice for LARVAL forms of tapeworm infections?

A

Albendazole

  • cysticercosis
  • echinococcus granulosus (cystic hydatid disease
  • longer treatment duration 1-6 months risk of hepatotoxicity
41
Q

What is praziqueantel contra-indicated in?

A

for treatment of ocular cysticercosis

-destruction of the organism in the eye may damage the eye itself

42
Q

What is the drug of choice if there is a cystic hydatid disease due to Echinococcus granulosus (dog tapeworm in a human)?

A

Albendazole

-3 month treatment or longer

43
Q

What is that one morphology thing that Fitzy pointed out about Schistosomiasis? (specifically, S. mansoni)

A

There’s a little spicule thing under microscopy

44
Q

What is the drug of choice for all forms of Schistosomiasis?

A

Praziquantel

45
Q

What does schistosoma present as?

A

Eggs in intestine

Flukes in the liver

46
Q

Bioavailability of Praziquantel

A
  • rapidly absorbed
  • distributes into CSF
  • metabolized
  • Short half life
  • extensive first pass metabolism
  • extensive ptn binding
  • inactive metabolites
47
Q

What does praziquantel interfere with?

what does it cause?

A

calcium homeostasis

-causes falccid paralysis in adult flukes

48
Q

What is necessary for praziquantel’s antithelminthic effect?

A

formation of specific antibodies

49
Q

What does Praziquantel do exactly?

A

causes antigens within the parasite to be exposed to the action of host antibodies

50
Q

What are the protozoal infections?

A

Amebiasis

Giardiasis

51
Q

What are the anti-protozoal/antiamebic agents?

A

Metronidazole
Tinidazole
Nitazoxanide

52
Q

What are the luminal amebicides?

A

Iodoquinol
Diloxanide furoate
Paromomycin

53
Q

What is Metonidazole extensively used to treat?

A

infections caused by anaerobic organisms

  • Protozoa and amoeba: Trichomonas vaginalis, entamoeba histolytica, giardia lamblia
  • Bacteria: enterococcus species, clostridium
54
Q

What is unique about the metabolism of the 3 protozoa and the anaerobic bacteria?

A

they do not rely on pyruvate dehydrogenase

-so they have pyruvate ferredoxin oxidoreductase (PFOR) complex

55
Q

What activates metronidazole?

A

Pyruvate ferredoxin oxidoreductase (PFOR) complex

56
Q

So, what is the drug of choice for amediasis?

A

Metronidazole

57
Q

What drug is approved for the treatment of giardiasis as a single dose and is appropriate first-line therapy, considered to be superior to metonidazole?

A

Tinidazole

58
Q

Adverse effects of Metronidazole/Tinidazole

A
  • METallic taste
  • Disulfiram-like reaction: severe symptoms associated with intake of alcohol and medication “disulfiram”
  • abdominal distress, vomiting, flushing, headache
  • alcohol-withdrawal symptoms
59
Q

What are the therapeutic goals of treating Amebiasis?

A
  1. ) eliminate the invading trophozoites

2. ) eradicate intestinal carriage of the organism

60
Q

What could E. histolytica be referred to in a question stem or answer choice if the test writer wants to be annoying?

A

A one-celled parasite

61
Q

What doe E. histolytica present as?

A

loose feces, stomach pain, cramping

-severe symptoms from amebic dysentery include stomach pain, BLOODY stools, and fever

62
Q

What does E. histolytica form in the liver?

A

abscess

-rarely spreads to other parts of the body like the lung and the brain

63
Q

What is symptomatic, or invsive colitis treated with?

A

metronidazole followed by a luminal amebicide

64
Q

What are some luminal amebicides that we could use?

A

paromomycin, diiodohydroxyquin, or diloxanide furoate

-to eliminate intraluminal cysts

65
Q

What should asymptomatic patients with E. histolytic be treated with?

A

just an intraluminal agent alone…. makes sense

66
Q

What is Paromomicin?

A

aminoglycoside family (not orally absorbed)

  • Binds 30S ribosome of pathogen… disrupts protein synth
  • Drug of choice for colonization of intestine with E. Histolytica
  • alternative to metronidazole for E. histolytic infection during pregnancy
67
Q

What should patients with Giardiasis be treated with?

A

tinidazole (bolded)

-or metronidazole, or nitazoxanide as the drugs of choice

68
Q

What is Giardia lamblia?

A

a flagellated protozoan parasite, causes both epidemic and sporadic disease and is an important etiology of waterborne and foodborne diarrhea

69
Q

What are the symptoms of Giardiasis?

A

diarrhea, malaise, steatorrhea, abdominal cramps, bloating, flatulence, nausea, and especially in young children, weight loss and failure to thrive

GI Final (13 decks)

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