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Pharm Exam 4 > Antiparasitic Drugs > Flashcards

Antiparasitic Drugs Flashcards

1
Q

3 targets for antiparasitic therapy?

A
  • enzymes or processes only found in the parasite (PFOR, folate synth)
  • Enzyme or proceses found both in the host and parasite but REQUIRED for parasite (purine salvage)
  • Common biochemical functions found in both parasite and host, but with different pharmacological properties (DHFR, microtubule disrupt)
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2
Q

Entamoeba histolytica

  • causes what disease?
  • important life-cycle stuff?
A
  • amebiasis
  • cyst form in poop that infects (FECAL ORAL) and trophozoites that are in intestines and almost anywhere else (disseminated = absceses)
  • -> INTESTINES AND EVERYWHERE ELSE
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3
Q

Giardia lamblia

  • causes what disease?
  • important life-cycle stuff?
A
  • Giardiasis
  • cyst from (dormant) and trophozoite form (growing & moving) in intestines
  • ->STAYS IN INTESTINES
  • FECAL ORAL
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4
Q

Trichomonas vaginalis

  • causes what disease?
  • important life-cycle stuff?
A
  • trichomoniasis
  • SEXUALLY TRANSMITTED
  • ONLY trophozoite form
  • ALWAYS ONLY IN UROGENITAL TRACT
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5
Q

*Tx for Trichomoniasis, giardiasis, and amebiasis?

MOA?

A

-Metronidazole (good for anaerobes aka parasites)
-targets pyruvate ferredoxin oxidoreducatase (PFOR) - converts pyruvate to acetyl CoA
==>HUMANS DO NOT HAVE PFOR

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6
Q

Metronidazole

  • tx for what?
  • MOA?
  • inactive/active
  • reactive intermediates
A
  • trichomoniasis, amebiasis, giardiasis
  • electron sink –> takes electrons away from ETC chain (takes away energy source)
  • reactive intermediates bind protein and DNA==> disruption
  • ACTIVATED by PFOR enzyme in anaerobic conditions
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7
Q

Metronidazole

  • tx for what?
  • side effects?
A
  • trichomoniasis, amebiasis, giardiasis
  • *disulfiram effect = avoid ETOH
  • vomit, diarrhea, abdominal issues
  • headache, dry mouth metalic taste
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8
Q

Is metronidazole safe for pregnancy?

A

Yes ok but discouraged during 1st trimester

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9
Q
  • How long is treatment for trichomoniasis?
  • Special thing about tx?
  • method for administration?
A
  • 7 day tx ORALLY
  • must also tx sexual partners
  • oral but topical gel or vaginal suppository if woman doesnt respond well to oral
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10
Q

Giardiasis - tx duration and dosing?

A

1) metronidazole
- TID for 5 days
- 90% success rate
2) nitazoxanide

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11
Q

Amebiasis

  • tx dosing and duration?
  • problem with tx amebiasis?
A
  • tid for 7-10 days
  • metronidazole treats the SYMPTOMATIC disease - so it helps with the bloody diarrhea due to trophozoite form – BUT WHAT ABOUT CYST FORM? – NEED TO FOLLOW UP WITH IODOQUINOL OR PAROMOMYCIN
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12
Q

What drug is vital for extra-intestinal amebiasis?

A

Metronidazole! - helps with liver and brain abscesses or elsewhere - metro penetrates tissues very well

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13
Q
  • metronidazole resistance?

- mechanism for resistance?

A
  • RARE but some showing up

- dec PFOR activity and inc other oxidoreducatase activity

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14
Q

What drugs to give/add to kill cyst form of amebiasis & giardiasis?

A

iodoquinol or paromomycin

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15
Q

Iodoquinol

  • MOA?
  • where is this drug good at killing parasite bastards?
A

-UNK MOA
-not absorbed well into system
-effective killing of E. histolytica cysts (and trophozoites) in LUMEN but it can disseminate so not complete fix
-good for giardia which has cysts only in lumen
ALSO kills the trophs

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16
Q

Problems with Iodoquinol tx?

A

1) adverse effects are infrequent - maybe GI BUT must take with meal to avoid GI tox
2) in children high dose for long term=optic atrophy and perm vision loss
3) 20 day long tx!

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17
Q

Paromomycin

  • MOA?
  • where is this drug good at killing parasite bastards?
A
  • UNK MOA
  • kills cyst for E histolytica in the LUMEN of intestine
  • NO killing of trophozoite forms in EXTRA-INTESTINAL AREAS
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18
Q
  • Paramomycin dosing and frequency?

- why better than iodoquinol?

A
  • tid for 7 days
  • iodoquinol is for 20 days so to have a patient take metronidazole for a week and then iodoquinol for 20 days = poor patient compliance
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19
Q

Cryptosporidium parvum

  • transmission?
  • symtpoms?
  • healthy vs immunosuppressed?
A
  • water-borne
  • watery diarrhea
  • healthy = self limited –> just rehydrate
  • immunocomp = diarrhea - chronic and fatal
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20
Q

Cryptosporidium parvum

  • Tx?
  • MOA?
A

-nitazoxanide
-INTERFERES with PFOR = disruption of anaerobic metabolism
(metronidazole is ACTIVATED by PFOR)

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21
Q

nitazoxanide

  • MOA?
  • Tx for?
A
  • Cryptosporidium parvum AND GIARDIASIS

- INTERFERES with PFOR = disruption of anaerobic metabolism

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22
Q

Pneumocystis jirovecii

  • tx?
  • MOA?
  • Why does this work?
A

-Trimethoprim-sulfamethoxazole = folate synth inh

  • parasitic protozoa must synthesize their folic acid while humans can get from diet
  • Low concentration wont INH OUR DHFR ENZYME
  • combining drugs has additive effect bc it hits two enzymes in folate synth path
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23
Q

Toxoplasma gondii

  • tx?
  • MOA?
  • Why does this work?
A

-Pyrimethamine-sulfadiazine = folate synth inh

  • parasitic protozoa must synthesize their folic acid while humans can get from diet
  • Low concentration wont INH OUR DHFR ENZYME
  • combining drugs has additive effect bc it hits two enzymes in folate synth path
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24
Q

Pharmacodynamics for Pyrimethamine-sulfadiazine and TMP-SMX?

A

-oral and good absorption and distribution

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25
Q

Sulfonamide side effects?

A
  • *RASH - Crystalluria - hemolysis - GI intolerance

- Folate deficiency

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26
Q
  • Toxoplasmosis
  • Tx of choice?
  • dosing-active disease and maintenance?
A
  • pyrimethamine-sulfadiazine
  • higher doses for active treatment
  • lower doses for long term maintenance
  • does not help with dormant tissue cyst
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27
Q
  • Resistance to TMP-SMX and pyrimethamine-sulfadiazine?

- Mechanism for resistance?

A
  • widely reported

- amino acid mutations in target enzymes

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28
Q

Pyrimethamine-sulfadiazine tx of choice for?

A

toxoplasmosis

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29
Q

Pneumocystis jirovecii

  • Tx of choice
  • dosing-active disease and maintenance?
A
  • Trimethoprim-sulfamethoxazole (TMP-SMX)
  • high dose for active disease
  • low dose for long term maintenance
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30
Q

Malaria

-life cycle?

A

-begins in mosquito and bites human –> hepatic stage (replication) –> blood stream cycle (playing with RBCs)

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31
Q

Hepatic stage Malaria - DRUG?

A

-primaquine

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32
Q

Blood stream stage Malaria -DRUG?

A

-cloroquine
-quinine
-mefloquine
…

33
Q

Chloroquine

  • MOA?
  • Dosing?
  • Side effects
A
  • messes with ability of parasite to detoxify compounds generated during Hb degredation
  • once weekly for prophylaxis
  • higher doses 4x onver 48 hrs
  • headache, nausea, vomit, blurred vision, dizzy, fatigue, confusion
34
Q

Chloroquine is effective against which stage and which species of malaria?

A
  • kills asexual erythrocytic stages

- ALL SPECIES of plasmodium

35
Q

Chloroquine

  • Resistance?
  • Mechanism of resistance?
A
  • HUGE - limited use
  • esp P Falciparum & Vivax

-rapid export pump

36
Q

Quinine

-MOA?

A
  • hits the digestive vacuoles - interferes with Hb metabolism/detox
  • complex with parasite DNA = issue with replication and transcription
37
Q

Quinine

-Side effects?

A
  • Poorest therapuetic ratio of all antimalarials
  • CINCHONISM - tinnitis, temp hearing loss, headache, nausea, vomit, visual disturbances
  • HYPOGLYCEMIA - quinine induced release of insulin.
38
Q
  • Is quinine used for prophylaxis?

- What are the prophylaxis drugs?

A
  • NOT QUININE
  • chloroquine
  • mefloquine
  • primaquine
  • malarone (used with chloroquine)
  • doxycyclne
39
Q

Quinine is effective against which stage and which species of malaria?

A
  • kills asexual erythrocytic stage

- kills ALL SPECIES of plasmodium

40
Q

Resistance to quinine?

A

-yes esp in asia

41
Q

Mefloquine

-MOA?

A
  • like quinine (hits the digestive vacuoles - interferes with Hb metabolism/detox
  • complex with parasite DNA = issue with replication and transcription)
42
Q

Mefloquine

  • Toxicity?
  • Dosing?
A
  • SOME neuropsychiatric reactions in small number patients

- long half life = easy weekly dosing

43
Q

Mefloquine is effective against which stage and which species of malaria?

A
  • kills asexual erythrocytic stage

- kills ALL SPECIES of plasmodium

44
Q

Primaquine

-MOA?

A
  • needs to be activated by host metabolism
  • interferes with mitochon ETC
  • interferes with pyrimidine synthesis
45
Q

ONLY drug for liver stage of malaria?

-good for which species and which cycle form??

A
  • primaquine
  • vivax and ovale
  • these two are only ones with hypnozoite form
46
Q

Primaquine

-toxicity?

A

-must check for G6PD deficiency
==> RBC lysis - hemolysis

SCREEN FOR THE G6PD STATUS

47
Q

What drug must you give for vivax and ovale species of malaria?

A

-Primaquine to kill the hypnozoites in the liver

48
Q

Malarone

  • combo of what drugs?
  • MOA?
  • Effective against which species?
A
  • atovaquone and proguanil
  • atova = MOA UNK - ALL SPECIES - lipophilic so take with fatty meal
  • prog = MOA= DHFR (dihydrofolate reductase) inhibitor
  • p falcip
49
Q

Malarone

-good for treating which species?

A

P falciparum

50
Q

Doxycycline

  • MOA?
  • tx how?
  • side effects?
A
  • inh growth by messing with protein synthesis
  • use in combo with other drugs
  • photosensitivity & staining teeth in children
  • -DO NOT give to children and pregnant women
51
Q

What are the chinese wormwood extract drug derivatives?

A

arteminisin derivs

52
Q

Arteminisin Derivatives

  • MOA?
  • good for which species of malaria?
A
  • interacts with iron = radical damage of membrane

- ALL species of plasmodium

53
Q

Enterobius vermicularis

-disease name?

A

pinworm

54
Q

Ascaris lumbricoides

-disease name?

A

ascariasis

55
Q

Necator americanus

-disease name?

A

-hookworm

56
Q

Trichuris trichiura

-disease name?

A

whipworm

57
Q

Strongyloides stercoralis

-disease name?

A

strongyloidiasis

58
Q

Tapeworms are?

A

cestodes

59
Q

Fluke worms are?

A

trematodes

60
Q

Antihelminthic MOA?

A

1) inhibit mitosis in parasite (benzimidazole compounds)

2) cause muscle paralysis of parasite (ivermectin, pyrantel pamoate and praziquantel)

61
Q
  • What are the benzimidazole compounds?

- Which is most absorbed?

A
  • albendazole
  • mebendazole
  • thiabendazole

-ALL have poor absorption (GOOD BC WORM IS IN GI LUMEN) but thiabendazole is most absorbed = most toxicity

62
Q

WHich is the most toxic benzimidazole compound?

  • Side effects?
  • MOA?
A
  • thiabendazole - most absorption
  • GI -anorexia, nausea, vomit
  • CNS - delirium, hallucinations

ALL inhibit mitosis in parasite

63
Q

How to administer benzimidazoles?

A
  • On an empty stomach
  • With fatty meal to kill worms more in tissue

inhibit mitosis in parasite

64
Q

resistance to benzimidazoles?

A

not a problem in human medicine

65
Q

Contraindication for benzimidazoles?

A

-Prego and if under 2 yo

66
Q

Albendazole and mebendazole good for killing? Dosing?

A
  • ascariasis
  • pinworm
  • hookworm
  • whipworm

Single high dose but meben can be given 3x lower dose

inhibit mitosis in parasite

67
Q

Thiabendazole good for killing what bugs?

-MOA?

A

-second line for strongyloidiasis (intestinal and tissue infection) – IVERMECTIN IS #1

inhibit mitosis in parasite

68
Q
  • What drug is given to treat cutaneous larval migrans?

- Transmission/How do you get cutaneous larval migrans?

A
  • thaibendazole topical prep

- from dog or cat hookworms - dont play with poop

69
Q

Ivermectin

  • MOA?
  • tx for what kinds of infections?
A
  • cause muscle paralysis of parasite = hyperpolarization

- for intestinal and extra intestinal infections

70
Q

Drug of choice for strongyloides?

A

ivermectin - no resistance

71
Q

Obscure/rare tropical infection - probs which drug?

A

ivermectin

72
Q

Pyrantel pamoate

  • MOA?
  • good for which infections?
A
  • cause muscle paralysis of parasite - nicotinic agonist in somatic muscles = depolarizing blockade
  • most good toxicity for intestinal nematodes
73
Q

Pyrantel pamoate - drug of choice for what condition?

A

-pinworm!!

-Tx the WHOLE FAMILY
Single dose and 2nd dose in 2 weeks

74
Q

Only drug used to treat tapeworms (Cestodes) and fluke (trematodes)?

A

-Praziquantel

75
Q

praziquantel

MOA?

A

-cause muscle paralysis of parasite = increase Ca permeability of tegument covering of worm
== depolarizing block
== more detecable by immune system

76
Q

Fluke drug and dosinng?

A

-praziquantel - 3 doses in 1 day

77
Q

Tapeworm drug and dosing?

A

-praziquantel - single dose

78
Q

Cysticercosis drug and dosing?

A

-praziquantel- 2 week tx

79
Q

no resistance or rare with which drugs?

A
  • bendazoles for helminthic inf
  • ivermectin for strongyloides
  • metronidazole - for amebiasis, thrichomoniasis, giardiasis

Pharm Exam 4 (10 decks)

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