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Pharm exam 4 > Antiparasitics > Flashcards

Antiparasitics Flashcards

1
Q

3 targets for antiparasitic chemotherapy

A
  1. Enzyme or processes found only in the parasite - few (PFOR; folate synthesis)
  2. Enzymes/processes found in both the host and parasite but indispensable only in the parasite - purine salvage pathway
  3. Common biochemical functions found in both parasite and host, but with different pharmacological properties (DHFR; microtubule disrupters)
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2
Q

waht parasites can metronidazole treat

A

Giardia

Entamoeba

Trichomonas

  • organisms possess PFOR (we don’t have this)
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3
Q

MOA of metronidazole

A

electron “sink”

inactivated under anaerobic conditions by PFOR - reactive intermediates form which bind to and disrupt protein and DNA structure/function

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4
Q

SE of metronidazole

A

GI

HA, dry mouth, metallic taste

Disulfiram-like effect - avoid alcohol consumption**

safe during pregnancy

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5
Q

what is the drug of choice for treating SYMPTOMATIC amebiasis

A

Metronidazole - follow with more potent luminal amebicide (idoquinol or paromycin) to eradicate non-invasive cyst forms

effective in treating invasive intestinal disease as well as extraintestinal amebiasis (liver and brain abscesses)

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6
Q

what is effective at eliminating trophozoite and cyst forms of E. histolytica from the LUMEN of the intestines?

no activity against trophozoidte forms in tissues

A

Idoquinolol

Paromomycin

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7
Q

what drug has been associated with optic atrophy and permanent vision loss in children who were administered high doses

A

idoquinolol

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8
Q

when is idoquinolol or paromomycin used

A

treats ASYMPTOMATIC or mild cases of amebiasis

in severe cases it should be used following metronidazole

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9
Q

MOA of paromomycin

A

aminoglycoside antibiotic

- inhibits protein synthesis in bacteria

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10
Q

idoquinolol and paromoycin

  1. oral or IV?
  2. absorbed well or poorly?
A
  1. oral

2. poorly

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11
Q

Adverse effects of paromycin

A

Abdominal discomfort and diarrhea

less toxic than idoquinolol

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12
Q

Like idoquinolol, ___ is used to treat asymptomatic or mild cases of amebiasis. Severe cases used follow mitronidazole

A

Paromomycin

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13
Q

wha tis used to treat C. parvum (OI)

A

Nitazoxanide

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14
Q

MOA of nitazoxamide

A

interferences with PFOR - disruption of anaerobic metabolism

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15
Q

Nitazoxanide:

1 (oral/IV/parenteral) suspension approved and indicated for tx of 2 and 3 in individuals 4 years of age

A
  1. oral
  2. Crptosporidiosis
  3. Giardiasis
  4. 1+
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16
Q

what folate synthesis inhibitor is used to treat Pneumocystic jirovecii (OI)

A

Trimethoprim-sulfamethoxazole

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17
Q

what folate synthesis inhibitior is used to treat toxoplasma gondii?

A

Pyrimethamine-sulfadiazine

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18
Q
  1. MOA of sulfonamides (sulfadiazine, sulfamethoxazole)

2. diaminopyrimidines (pyrimethamine, trimethoprim)

A

folate synthesis inhibitors

  1. PABA anolog; inhibits prodcution by dihydropteroate synthase
  2. inhibitor of DHFR - prevent THF formation = selective toxicity
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19
Q

adverse reactions for sulfonamides

A

rash

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20
Q

treatment of choice for toxoplasmosis

  • does not effect dormant tissue cyst
A

pyrimethamine-sulfadiazine

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21
Q

antimalarial:

  • oral administration
  • T1/2 ~4days
  • higher doses adminstered 4 times over 48 hours for clinical disease
A

chloroquine

22
Q

SE of chloroquine

A 
HA
GI
Blurred vision
Dizzy
Fatigue
Confusion
23
Q

what stage will chloroquines and quinine eliminate

A

asexual erythrocytic stages of all species of plasmodium

24
Q

resistance against chloroquine

A

YES
- limited use

rapid export mechanism

25
Q

which antimalarials has the poorest therapeutic:toxic ratio and is generally not used for chemoprophylaxis due to its toxicity

A

Quinine

26
Q

SE of quinine

A

Cinchonism: tinnitus, temporary hearing loss, HA, nausea, vomiting, visual disturbance

Hypoglycemia

27
Q

toxicity of mefloquine?

A

Severe neuropsychiatric reactions in pts receiving TREATMENT

28
Q

what is mefloquine effective against

A

all species of Plasmodium (no resistance)

29
Q

what antimalarial should people be screened for G6PD? why?

A

Primaquine

RBC lysis in persons with G6PD deficiency

30
Q

Drug of choice for treating dormant liver (hypnozoite) forms of P. vivax and P. ovale

or after prophylaxis with chlorquine in individuals who have substantial risk of exposure to these organisms

A

Primaquine

31
Q

which antimalarial has a longer half life (14 days), better tissue distribution than primaquine, single dose as effective as 2 weeks of primaquine, but same problem with GP6PD?

A

Tafenoquine

32
Q

Antimalarial - Malarone

Combination of atovaquone (lipophilic, activity against all Plasmodium) and 1

highly efficacious in tx of 2 as well as prophylaxis

no resistance

A
  1. proguanil (inhibit DHFR - not used alone due to resistance)
  2. P. flaciparum
33
Q

what protein synthesis inhibitors can also be used for the treatment and prophylaxis of malaria? (effective against all species of plasmodium)

A

Doxycycline - primarily prophylaxis

34
Q

SE of doxycycline

A

photosensitivity dermatitis

staining of teeth in children

***contraindicated in children and pregnant women

35
Q

In 2009 what drug combination therapy was approved by the FDA for the treatment of P. flaciparum infection

A

Artemether:lumefantrine

36
Q

what drug can be used for all human malaria parasistes and multi-drug resistant strains of P. flaciparum

A

Artemisinin derivatives

37
Q

MOA of antihelmintics

A

inhibit mitosis in parasites (benzimidazole cmpds)

cause muscle paralysis of parasite (ivermectin, pyrantel, pamoate, prazinquantel)

38
Q

of the benzimidazoles (albendazole, mebendazole, thiabendazole) whcih is more efficiently absorbed accounting for its greater toxicity

A

thiabendazole

39
Q

Benzimidazoles:

generally adminitered on an 1 when used to treat luminal nematodes

may be administered after a 2 meal to increase absorption and act on tissue dwelling helminths

A
  1. empty stomach

2. fatty

40
Q
  1. toxicity of thiabendazole?

2. albendazole and mebendazole?

A
  1. GI and CNS disturbance (delirium, hallucination)

2. GI

41
Q

when is bezimidazoles contraindicated

A

pregnancy

use in children under 2

42
Q

what infections can albendazole and mebendazole treat

A

ascariasis

pinworm

whipworm

hookworm

single dose is efficient

43
Q

Thiabendazole is the second line drug used in the treatment of 1

Topical preparation is used in the treatment of 2 caused by the larval forms of dog and cat hookworms

A
  1. strongyloidiasis (intestinal and tissue infection)

2. cutaneous larval migrans

44
Q

MOA of ivermectin (antihelmintic)

A

hyperpolarization in muscle cells - paralysis

used for intra and extraintestinal infections

45
Q

what is the drug of choice for treating strongyloidiasis (inestinal and extrainstestinal)

A

Ivermectin

46
Q

Ivermectin is used in treating ___ dwelling nematodes include what?

A
  1. tissue
  • O. volvulus (river blindness)
  • L. Ioa (eye worm)
  • Filarial worms: W. bancrofti and B. malayi
47
Q

MOA of pyrantel pamoate

A

activates cholinergic nictonic receptors in the somatic muscles of nematodes - depolarizing neuromuscular blockade

48
Q

what does pyrantel pamoate have selective toxicity for

A

intestinal nematodes

49
Q

what is the drug of choice for treating pinworms who else needs to be treated if someone has pinworms

A

Pyrantel pamoate - **treatment of entire household

50
Q

what drug is used to treat tapeworm (cestode) and fluke (trematode) infection

A

Praziquantel

51
Q

MOA of praziquantel

A

increase Ca2+ permeability of worms tegument – depolarization, spastic paralysis and increase immue detection

52
Q

tx of praziquantel in:

  1. flukes
  2. tapeworms
  3. cysticercosis
A
  1. 3 doses in a single day
  2. single dose
  3. 2 weeks

Pharm exam 4 (15 decks)

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