Anthelmintic Drugs

Question 1

What are the two principles of anthelmintic drugs?

Answer 1

1. the drugs are not absorbed by the host (placed in host environment) - mebendazole
2. the drug acts on the parasite, but not the host - ivermectin

Question 2

Giant roundworms: Ascariasis, are most prevalent infestation worldwide. Adult worms inhabit the intestine and are typically asymptomatic but serious complications can occur if they migrate. What is the drug of choice for this nematode?

Answer 2

mebendazole, albendazole, and pyrantel

Question 3

Pinworms: Enterobiasis is most common in the US. What is the drug of choice for this nematode?

Answer 3

mebendazole, albendazole, and pyrantel

Question 4

Hookworms: Ancylostomiasis and Necatoriasis occurs commonly in rural areas where people go barefoot. What is the drug of choice for this nematode?

Answer 4

mebendazole, albendazole, and pyrantel

Question 5

Threadworm: Strongyloidiasis is common in the Southern US. This infestation is always treated with this drug

Answer 5

Ivermectin

Question 6

Whipworm: Trichuriasis is common worldwide. Severe infestation is treated with this drug.

Answer 6

Mebendazole

Question 7

What is the MOA of mebendazole?

Answer 7

inhibits beta-tubulin polymerization which inhibits microtubule formation - inhibits glucose uptake and decreases ATP formation

note: no effect on host glucose metabolism

Question 8

What are the adverse effects of mebendazole?

Answer 8

diarrhea, abdominal pain

Question 9

What is the contraindication for mebendazole?

Answer 9

embryotoxic and tertogenic in rats - should be avoided during pregnancy

Question 10

What is the dosage for mebendazole for treating round worms (Ascariasis)?

Answer 10

500 mg once or 100 mg x 3 d

Question 11

What is the dosage for mebendazole for treating pinworms (Enterobius)?

Answer 11

100 mg once, repeat in 2 wks

Question 12

What is the MOA of Ivermectin?

Answer 12

causes paralysis of the pharyngeal muscles of worm by activating glutamate-gated chloride channels in invertebrate

Question 13

What are the adverse effects of Ivermectin?

Answer 13

GI upset, dizziness, vertigo and sedatio; Mazotii reaction in patients treated for onchocerciasis

Question 14

Ivermectin is also used for onchocerciasis, a microfilarial infection, which is responsible for ____ ____

Answer 14

river blindness

Question 15

What is the MOA of pyrantel?

Answer 15

causes persistent depolarization and consequently neuromuscular paralysis of the worm

note: paralyzed worms are cleared in feces

Question 16

What are the adverse effects of pyrantel?

Answer 16

occasional GI disturbances, headache, dizziness, rash, fever

Question 17

There are two Cestodes (tapeworms). One comes from beef/pork and the other comes from fish. Name each.

Answer 17

Taeniasis: beef/pork

Diphyllobothriasis: fish

Question 18

For each of the following Trematodes (flukes), give their habitat within the human and where they come from:
Shistosomiasis
Fasioliasisi
Fasciolopsiasis

Answer 18

Shistosomiasis: blood fluke - snails
Fasioliasisi: liver fluke - sheep
Fasciolopsiasis: intestinal fluke - SE Asia

Question 19

What is the drug of choice for all tapeworms and flukes besides Fasciola hepatica?

Answer 19

Praziquantel

Question 20

What is the drug of choice for Fasciola hepatica?

Answer 20

bithionol

Question 21

What is the MOA of Praziquantel?

Answer 21

increases the calcium permeability of schistosome tegument and causes its depolarization - induces strong and instantaneous contraction in worms and consequently dislocates worms in the intestine

Question 22

What are the adverse effects of Praziquantel?

Answer 22

occasional sedation, abdominal discomfort, fever, sweating, nausea, headache, dizziness

Question 23

What is the rate of absorption of Praziquantel?

Answer 23

rapid - following oral administration

half-life: 1-2 hours, 70% excretion within 24 hours