Antihelminthics

Question 1

Most common helminthic infection in US

Answer 1

Enterobiasis (pinworm)

Question 2

What drug is a benzimidazole?

Answer 2

Albendazole

Question 3

MOA of albendazole

Answer 3

• Inhibit polymerization of parasite B-tubulin
• prevent formation of cytoplasmic microtubules
• disrupt motility and uptake of glucose (slow death)
• best with high fat meal
• first pass metabolism to active form

Question 4

Albendazole uses

Answer 4

• cestodes
• roundworms
• pinworms

Question 5

Adverse reactions of albendazole

Answer 5

• generally well tolerated
• teratogenic effects
• long term —> liver toxicity (liver function tests)
• bone marrow suppression

Question 6

Which antihelminths should be avoided in pregnancy?

Answer 6

Albendazole

Ivermectin

Question 7

Neurocysticercosis

Answer 7

From undercooked pork contaminated with taenia solium (tapeworm eggs)

Cysts in brain can cause seizures

Question 8

MOA of praziquantel

Answer 8

• increase permeability of trematode and cestode cell membranes to calcium —> paralysis, dislodgement, death

Question 9

Praziquantel uses

Answer 9

• drug of choice for schistosomiasis

- other trematode and cestode infections

Question 10

Drug of choice for schistosomiasis

Answer 10

Praziquantel

Question 11

Alternative to albendazole for cysticercosis

Answer 11

Praziquantel

Question 12

Adverse reactions of praziquantel

Answer 12

• generally well tolerated

- not clear whether symptoms are drug related or due to release of proteins from dying worms (fever, pruitis, rash)

Question 13

Roundworm infection

Answer 13

Ascariasis
Hookworm
Toxocariasis

Question 14

Cestode infection

Answer 14

Neurocysticercosis

Hydatid disease

Question 15

MOA pyrantel pamoate

Answer 15

• depolarizing neuromuscular blocking agent
• effective only within in GI
• persistent activation of parasite nicotinic Ach receptors and inhibition of AChE —> spastic paralysis —> expulsion of worms

Question 16

Alternative to albendazole for ascariasis and enterobiasis

Answer 16

Pyrantel pamoate

Question 17

What antihelminthic agent is OTC?

Answer 17

Pyrantel pamoate

Question 18

Pinworm infection

Answer 18

Denterobiasis

Question 19

Adverse reactions of pyantel pamoate

Answer 19

• generally well tolerated

- will produce NM blockade if given parenterally

Question 20

MOA ivermectin

Answer 20

• immobilization of worms by tonic muscle paralysis
• activate glutamate-gated Cl channels
• hyperpolarization of cell membrane
• P-glycoprotein efflux transporter pumps drug out of mammalian CNS

Question 21

Ivermectin uses

Answer 21

• nematode and arthropods infections in vet medicine
• onchocerciasis, lymphatic filariasis and intestinal nematodes in humans
• scabies and head lice

Question 22

Onchocerciasis

Answer 22

River blindness

Question 23

Adverse reactions of ivermectin

Answer 23

• generally well tolerated
• Mazzotti recation
• Teratogenic

Question 24

Mazzotti reaction

Answer 24

In onchocerciasis

Pruitis, rash, fever, lymphedema —> due to immune reaction to dying worms

Question 25

Drug for cestodes (tapeworm)

Answer 25

Praziquantel

Question 26

Drug for trematodes (flukes)

Answer 26

Praziquantel

Question 27

Drug for nematodes (pork roundworm)

Answer 27

Albendazole

Question 28

Drug for nematodes (filariae)

Answer 28

Ivermectin

Question 29

Drug for nematodes (pinworm)

Answer 29

Benzimidazoles or pyrantel pamoate

Question 30

Drug for nematodes (hookworm)

Answer 30

Albendazole

Question 31

Drug for nematodes (whipworm)

Answer 31

Albendazole

Question 32

Drug for nematodes (threadworm)

Answer 32

Ivermectin

Question 33

Enterobiasis

Answer 33

Pinworm

Most common infection in US

Question 34

Albendazole pregnancy?

Answer 34

No!