Antiprotozoals

Question 1

Metronidazole

Answer 1

Nitroimidazole antibiotic

Effective in trichomoniasis, amebiasis, and giardiasis (not in Canada)

Nitro group is converted to a radical anion by anaerobic organisms, this radical and others generated target DNA and other biomolecules

Rare neurotoxicity (encephalopathy, ataxia)

Interacts with alcohol and should not be taken during the first trimester of pregnancy

Question 2

Tinidazole

Answer 2

Nitroimidazole antibiotic

Effective in trichomoniasis, amebiasis, and giardiasis (not in Canada)

Nitro group is converted to a radical anion by anaerobic organisms, this radical and others generated target DNA and other biomolecules

Rare neurotoxicity (encephalopathy, ataxia)

Interacts with alcohol. Safe alternative to metronidazole during the first trimester of pregnancy.

Question 3

Iodoquinol

Answer 3

Effective against E. histolytica, typically with established resistance to metronidazole

MOA unknown

Optic atrophy
Permanent loss of vision

Question 4

Paromomycin

Answer 4

Aminoglycoside

Treats cryptosporidiosis, giardiasis, and trichomoniasis. Drug of choice (in combination with metronidazole) for E. histolytica

Nephrotoxicity
Ototoxicity

Question 5

Nitazoxanide

Answer 5

Treats giardiasis and cryptosporidiosis

Proposed mechanism is due to inhibition of pyruvate:ferredoxin oxidoreductase enzyme-dependent electron transfer, an important aspect of parasite anaerobic metabolism

Teratogenic (in animal studies)

Question 6

Co-Trimoxazole

Answer 6

Combination therapy of sulfamethoxazole and trimethoprim to treat toxoplasmosis and pneumocystis pneumonia

Question 7

Suramin

Answer 7

Treatment of early stage sleeping sickness

Binds to plasma proteins and enters the parasite via endocytosis, where it inhibits key enzymes

Renal toxicity
Leukopenia

Question 8

Pentamidine

Answer 8

Treatment of early-stage sleeping sickness

Taken into parasite through energy-dependent carriers and thought to interact with DNA

Hypoglycemia

Question 9

Melarsoprol

Answer 9

Treatment of late-stage sleeping sickness

Enters the CNS in high concentrations and interacts with protein sulfhydryl groups, inactivating enzymes

Highly toxic
Encephalopathy
Occasional immediate fatality

Question 10

Eflornithine

Answer 10

Treatment of late-stage sleeping sickness

Irreversibly inhibits parasite ornithine decarboxylase enzyme

Seizures
Reversible hearing loss

Question 11

Nifurtimox

Answer 11

Nitrofuran analog

Activated by NADH dependent nitroreductase in mitochondria leading to nitro free radicals that kill the parasite

Peripheral neuropathy
Neurotoxicities
Leukopenia

Question 12

Benznidazole

Answer 12

Benznidazolea nitroimidazole analog

Activated by NADH dependent nitroreductase in mitochondria leading to nitro free radicals that kill the parasite

Peripheral neuropathy
Neurotoxicities
Leukopenia