Antiprotozoals

Question 1

Metronidazole

Answer 1

Antiprotozoals Agent

Characteristics:
- Targets Amebiasis,
Trichomoniasis,
Giardiasis
- Nitroimidazole Antibiotic
- Prodrug that needs reductive activation

MOA:
- Nitro group is converted to a reactive radical anion by susceptible anaerobic organisms using reductive activation
–> Radical anion targets DNA and other biomolecules of the parasite

AE:
- Rare neurotoxicity (Encephalopathy, Ataxia)
- Teratogenic
- Interact with alcohol and disulfiram

Question 2

Tinidazole

Answer 2

Antiprotozoals Agent

Characteristics:
- Targets Amebiasis,
Trichomoniasis,
Giardiasis
- Nitroimidazole Antibiotic
- Prodrug that needs reductive activation
- Safe in pregnancy

MOA:
- Nitro group is converted to a reactive radical anion by susceptible anaerobic organisms using reductive activation
–> Radical anion targets DNA and other biomolecules of the parasite

AE:
- Rare neurotoxicity (Encephalopathy, Ataxia)
- Interact with alcohol and disulfiram

Question 3

Iodoquinol

Answer 3

Antiprotozoals Agent

Characteristics:
- Targets Amebiasis (E. Histolytica)

MOA:
- Unknown, thought to effect protozoa metabolism

AE:
- Optic atrophy
- Permanent loss of vision
- Caution in patient with Neuropathies or Thyroid Diseases

Question 4

Paromomycin

Answer 4

Antiprotozoals Agent

Characteristics:
- Aminoglycoside
- Targets Cryptosporidiosis, Giardiasis, Trichomoniasis

• Combined with metronidazole for treating E. histolytica

MOA:
- Bind irreversibly to 30S ribosomal subunit
–> Inhibits protein synthesis (Trap ribosomes at the AUG start codon)

AE:
- Nephrotoxicity
- Ototoxicity

Question 5

Nitazoxanide

Answer 5

Antiprotozoals Agent
(PFOR Inhibitor)

Characteristics:
- Giardiasis,
Cryptosporidiosis

MOA:
- Inhibits pyruvate:ferredoxin oxidoreductase enzyme dependent electron transfer
–> Interferes with parasite anaerobic energy metabolism

Question 6

Co-Trimoxazole

Answer 6

Antiprotozoals Agent

Characteristics:
- Targets Toxoplasmosis,
Pneumocystis Pneumonia
- Sulfamethoxazole + Trimethoprim

MOA:
- Sulfamethoxazole is a sulfa antibiotics
- Trimethoprim is a Folate acid antagonist
–> Inhibits folate acid synthesis needed by protozoa

Question 7

Suramin

Answer 7

Drug for Trypanosomiasis

Characteristics:
- Treats Sleeping Sickness (Early Stage)

MOA:
- Binds to plasma proteins and enters parasite via endocytosis
–> Inhibits key enzymes (Glycolysis enzymes, Thymidine kinase, Dihydrofolate reductase)
–> Induces gradual destruction of organelles

AE:
- Renal Toxicity
- Leukopenia (In people with AIDS)

Question 8

Pentamidine

Answer 8

Drug for Trypanosomiasis

Characteristics:
- Treats Sleeping Sickness (Early Stage)

MOA:
- Taken into parasite via energy-dependent carrier
–> Interacts with DNA inhibiting DNA and protein synthesis

AE:
- Hypoglycemia

Question 9

Melarsoprol

Answer 9

Drug for Trypanosomiasis

Characteristics:
- Treats Sleeping Sickness (Late Stage)
- Prodrug, is converted into the active melarsen oxide
- Used in CNS infection as it enters CNS in high concentrations

MOA:
- Interacts with protein sulfhydryl groups
–> Enzyme inactivation

AE:
- Encephalopathy
- Immediate fatality sometimes

Question 10

Eflornithine

Answer 10

Drug for Trypanosomiasis

Characteristics:
- Treats Sleeping Sickness (Late Stage)

MOA:
- Irreversibly inhibits Parasite Ornithine Decarboxylase (ODC) enzyme
–> Decreases formation of polyamines needed for cell replication

Question 11

Nifurtimox

Answer 11

Drug for Trypanosomiasis

Characteristics:
- Treats Chagas Disease
- Nitrofuran analog

MOA:
- Activated by NADH dependent nitroreductases in mitochondria
–> Generation of nitro free radicals that kill the parasite

Question 12

Benznidazole

Answer 12

Drug for Trypanosomiasis

Characteristics:
- Treats Chagas Disease
- Nitroimidazole analog

MOA:
- Activated by NADH dependent nitroreductases in mitochondria
–> Generation of nitro free radicals that kill the parasite