TBL 6 - Parasites and Antiparasitics

Question 1

What drug is used to treat asymptomatic Entamoeba histolytica?

Answer 1

Paromycin

Question 2

What drug(s) are used to treat symptomatic Entamoeba histolytica?

Answer 2

Nitroimidazoles and Paromycin

Question 3

What drug class does Paromycin belong to and what is its MoA?

Answer 3

It is an aminoglycoside, which is a 30s ribosomal inhibitor that blocks initiation complex formation.

Question 4

What are some examples of aminoglycosides?

Answer 4

Gentamicin, Tobramicin, Amikacin, Streptomycin, and Paromycin.

Question 5

What is the role of Paromycin when used for Entamoeba histolytica infections?

Answer 5

Eliminates intraluminal cysts/invading trophozoites.

Question 6

What is an adverse effect of paromycin?

Answer 6

GI discomfort.

Question 7

What are some examples of nitroimidazoles?

Answer 7

Metronidazole, Tinidazole, Benznidazole, and Fexinidazole.

Question 8

What is the MoA of nitroimidazoles?

Answer 8

Generate reactive intermediates and free radicals.

Question 9

What are some adverse effects of nitroimidazoles?

Answer 9

Metallic taste and disulfiram-like reaction (severe flushing, tachycardia, and hypotension).

Question 10

What is the treatment of choice to treat Giardia duodenalis?

Answer 10

Nitroimidazoles (Metronidazole) or Nitazoxanide

Question 11

What is the MoA of Nitazoxanide?

Answer 11

Same as nitroimidazoles; Generate reactive intermediates/free radicals.

Question 12

What is the treatment for Leishmania?

Answer 12

Amphotericin B, Miltefosine, and Pentavalent Antimonial (Stibogluconate)

Question 13

What is the MoA of Amphotericin?

Answer 13

Disrupts cell membranes by sequestering ergosterol which disrupts membrane integrity, leading to cell (fungal) death.

Question 14

What are some adverse effects of Amphotericin?

Answer 14

Infusion reactions, nephrotoxicity, hypokalemia, hypomagnesemia, and arrhythmias.

Question 15

What is the MoA of Miltefosine?

Answer 15

Interferes with cell membrane phospholipids, inhibits cytochrome c oxidase (mitochondrial function), and induces apoptosis-like cell death.

Question 16

What is the MoA of Pentavalent Antimonial (Stibogluconate)?

Answer 16

Inhibits parasitic glycolysis.

Question 17

What combination of drugs are used to treat Toxoplasma gondii?

Answer 17

Pyrimethamine, Sulfadiazine, and Leucovorin

Question 18

What is the MoA of SMX (Sulfamethoxazole) and Sulfadiazine?

Answer 18

Dihydropteroate synthase inhibitor.

Question 19

What is the MoA of Trimethoprim (TMX) and Pyrimethamine?

Answer 19

Dihydrofolate reductase inhibitor.

Question 20

What is the MoA of Leucovorin?

Answer 20

Is a reduced form of folic acid that is used to restore active folate stores.

Question 21

What are the adverse effects of Pyrimethamine, Sulfadiazine, and Leucovorin?

Answer 21

Sulfa allergies
Hypersensitivity reactions
Hemolytic anemia; avoid in G6PD deficiency
Photosensitivity
Kernicterus in infants
Avoid in pregnancy
Hyperkalemia
Bone marrow suppression

Question 22

What is the prophylactic treatment for Toxoplasma gondii?

Answer 22

TMP-SMX

Question 23

What medicine is used to treat taeniasis (from larvae and cysts)?

Answer 23

Praziquantel

Question 24

What is the MoA of praziquantal?

Answer 24

Increases cell permeability to Ca2+ causing strong contractions and paralysis, leading to detachment.

Question 25

What drugs are used to treat neurocysticercosis (from eggs)?

Answer 25

1-2 cysts: albendazole
More than 2 cysts: albendazole and praziquantel

Question 26

What is the MoA of albendazole (Triclabendazole)?

Answer 26

Inhibit microtubule synthesis and function causing decreased glucose uptake, leading to decreased ATP production.