Anti-Parasitic Flashcards by Michael Bouchard

3 targets for anti-parasitic chemotherapy

Enzymes/processes only found in parasite (few)
Enzymes/processes found in host and parasite but only desirable in parasite
Common biochemical functions found in both but with different properties

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3 intestinal lumen dwelling parasites

E. histolytica
Giardia lamblia
Trichomonas vaginalis

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Drug of choice for treating intestinal lumen dwelling parasites

Metronidazole (not ideal for cysts)

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MOA Metronidazole

Prodrug - activated by reduction

Selectively toxic to anaerobic organisms

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AE Metronidazole

headache, dry mouth, GI distress
Avoid alcohol consumption
Safe during pregnancy (discouraged during 1st trimester)

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Metronidazole for Trichomonas

treat sexual partners simultaneously

Topical if oral doesn’t work

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Metronidazole for Amebiasis

Amebicide - kills trophozoite
Drug of choice for symptomatic infections
Cysts - follow up with Iodoquinol or Paromomycin

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MOA Iodoquinol

unknown

effective at eliminating both trophozoite and cyst forms

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AE Iodoquinol

Gi discomfort, optic atrophy in children

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MOA Paromomycin

Aminoglycoside - inhibit protein synthesis

effective at eliminating both trophozoite and cyst forms

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Drug of choice for Cryptosporidium parvum

Nitazoxanide

Also treats Giardia

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MOA Nitazoxanide

interfere with PFOR - disrupt energy metabolism

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MOA Sulfonamides

PABA analogs inhibiting production of pteroic acid from PABA

“SULFA”

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AE Sulfonamides

rash, crystalluria, GI intolerance, hemolysis

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MOA Diaminopyrimidines

inhibit DHFR = no THF
Pyrimethamine
Trimethoprim

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RES Diaminopyrimidines

Point mutations in DHFR

Drug of choice for Toxoplasmosis

Pyrimethoxamine + Sulfadiazine
Low dose for HIV/IC
Does not effect cyst**

AE Pyrimethoxamine-Sulfadiazine

folate deficiency

Co-administer Leucovorin

Drug of choice for Pneumocystis jirovecii

Trimethoprim-Sulfamethoxazole (TMP-SMX)

Anti-malarial drugs

4 Quines + Doxy = Malarone
Chloroquine
Quinine
Mefloquine
Primaquine
Doxycycline 
Malarone

MOA Chloroquine

interfere with parasite ability to detoxify compounds

RES Chloroquine

huge resistance = low usefulness

Rapid export pump

MOA Quinine

digestive vacuoles
interfere with Hb degradation/detoxification
may interfere with parasite DNA

AE Quinine

poorest therapeutic-toxic rate
Cinchonism - hearing loss
Hypoglycemia - quinine-induced release of insulin **

MOA Primaquine

Prodrug - interferes with mitochondrial electron transport | Only drug available for activity against liver forms of P. vivax and P. ovale

AE Primaquine

Hemolytic anemia in pts with G-6-P deficiency | Must screen before

MOA Malarone

combination of Atovaquone and Proguanil - DHFR inhibition | Highly effective against P. falciparum

MOA Doxycycline

Interrupt protein synthesis

AE Doxycycline

skin/teeth discoloration and sensitivity | Contraindicated in children and pregnant women

MOA Benzimidazole

"BENDAZOLE" inhibit mitosis Treat: Ascariasis, pinworm, hookworm, whipworm

Thiabendazole

second line treatment for Strongyloidiasis | Topical treatment for cutaneous larval migrans

AE Thiabendazole

GI/CNS disturbances | Contraindicated in children <2 and pregnant women

MOA Ivermectin

Hyperpolarization of muscle cells causing paralysis | Drug of choice for Strongyloidiasis

MOA Pyrantel Pamoate

activates cholinergic nicotinic receptors in somatic muscles of nematodes causing paralysis Drug of choice for pinworm - treat entire household Selective toxicity to nematodes

MOA Praziquantel

Increased Ca permeability leading to hyperpolarization and paralysis Increased immune detection Treatment of tapeworm and fluke