52-Antiparasitic Drugs Flashcards

1
Q

3 targets for antiparasite therapy?

A

1-Enzymes or processes found only in the parasite (PFOR; folate synthesis)
2-Enzymes or processes found in both parasite and host but indispensable only in the parasite (purine salvage pathways)
3-Common biochemical functions found in both parasite and host, but with different pharmacologic properties (DHFR; microtubule disrupters)–different binding affinity to parasite and host

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2
Q

Metronidazole mechanism

A

activated by PFOR in anaerobic conditions. Used for trichomoniasis, giardiasis and amebiasis (doesn’t kill cyst forms in amebiasis)

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3
Q

Why follow up Metronidazole treatment with something else? what?

A

doesn’t kill cyst forms. Use Iodoquinol or paromomycin to eradicate cyst forms

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4
Q

Iodoquinol use and adverse effects

A

use to eliminate trophozoite and cyst forms of E. histolytica (amebiasis) in lumen (poorly absorbed)
causes optic atrophy and permanent vision loss in kids
also 20 day regimen!

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5
Q

Paromomycin

A

Similar to Iodoquinol, but less toxic and shorter regimen (7 days)

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6
Q

Nitazoxanide use and MOA

A

use for cryptosporidiosis (common in AIDS patients)

Interferes with PFOR

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7
Q

Sulfonamides

names and mechanism

A

sulfamethoxazole and sulfadiazine
PABA analogs that block folate synthesis by inhibiting dihydropteroate synthase. Pyrimethamine-Sulfadiazine treatment can induce folate deficiency so administer folinic acid to avoid deficiency

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8
Q

Diaminopyrimidines

names and mechanism

A

pyrimethamine and trimethoprim
inhibit the enzyme DHFR and block folate synthesis. Inhibits parasite DHFR at much lower concentrations than the mammalian.

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9
Q

sulfonamides adverse reactions

A

rash and hemolysis

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10
Q

Treatment choice for toxoplasmosis?

A

Pyrimethamine-Sulfadiazine

higher doses for active disease and lower dose for lifelong maintenance

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11
Q

Treatment for Pneumocystis jirovecii infection?

A

Trimethoprim-Sulfamethoxazole

higher doses for active disease and lower dose for lifelong maintenance

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12
Q

Chloroquine

A

malaria drug with big time resistance. Don’t give this one very often

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13
Q

Quinine

3 adverse

A
Poorest therapeutic:toxic ratio of all antimalarial drugs
causes cinchonism (vestibulocochlear) and hypoglycemia (which can already be a problem in chronic infection)
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14
Q

Mefloquine

A

malaria drug with neuropsychiatric reactions in .5% of patients being treated for malaria

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15
Q

Primaquine

use, adverse

A

The only antimalarial with activity against liver (hypnozoite) forms of P. vivax and P. ovale.
Can cause hemolysis in people with G6PD deficiency!

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16
Q

Malarone

A

malaria drug combination of atovaquone and proguanil.

proguanil inhibits DHFR

17
Q

Doxycycline

use, adverse

A

can be used for malaria prophylaxis or treatment.

causes photosensitivity dermatitis and stains teeth in children

18
Q

Artemisinin Derivatives

A

extracted from “chinese wormwood”

works against drug resistant strains.

19
Q

Antihelminthic drugs MOA

A

can inhibit mitosis (benzimidazoles) or cause muscle paralysis (ivermectin, pyrantel pamoate, and praziquantel)

20
Q

Benzimidazoles

names and side-effects/contraindications

A

Albendazole, mebendazole, thiabendazole

All have GI side-effects and thia has CNS disturbances. Contraindicated for pregnancy and kids under 2

21
Q

What drugs used to treat ascariasis, pinworm, hookworm and whipworm?

A

albendazole/mebendazole

22
Q

What to treat strongyloidiasis and cutaneous larval migrans?

A

Thiabendazole

23
Q

Ivermectin MOA and use?

A

causes hyperpolarization in muscle cells.

drug of choice for strongyloidiasis

24
Q

Pyrantel Pamoate MOA and use?.

A

activates cholinergic nicotinic receptors in nematodes which paralyzes them.
drug of choice for pinworm
“pyrantel pamoate paralyzed pinworm”

25
Q

Treatment of choice for tapeworm and fluke infections?

A

Praziquantel

26
Q

Praziquantel MOA, use/dose

A

increases calcium permeability of worm’s tegument

flukes: 3 doses single day
tapeworms: single dose
cysticercosis: two weeks