Dr. Roane Antiparasitics EXAM 3

Question 1

What are the 3 groups of Lice?

Answer 1

-Head lice
-Body lice
-Pubic lice (“crabs”)

Question 2

What are the drug classes associated with the treatment of Lice?

Answer 2

-Acetylcholinesterase inhibitors
-Spinosad – nicotinic receptor agonist (overstimulation is killing the insect)
-Ivermectin (lotion) – also used to treat worms

Question 3

Why are insects so susceptible to Acetylcholinesterase inhibitors?

Answer 3

Because their body is the major excitatory neurotransmitter in the insect central nervous system (CNS)

Question 4

What are the Acetylcholinesterase inhibitors?

Answer 4

-Pyrethrins (based on chrysanthemum flower)
-Organophosphates: Malathion (irreversible AChE inhibitor)
-Organochlorines: Lindane (not 1st line choice due to toxicity, persistent in the environment and in humans)

Question 5

Which compound was used to treat Antihelmintics?

Answer 5

Arsenicals (arsenic) - too toxic

(Trisenox: used to treat a form of leukemia)

Question 6

What would be an appropriate repellant to use?

Answer 6

-DEET = N,N-Diethyl-meta-toluamide
-safe to use, unless used long-term, heavy, frequent, and applied to the whole body

Question 7

Alternative repellant

Answer 7

Icaridin
Pro: odorless
Con: not as effective against mosquitos

Question 8

What would be an example of Nematodes
and how to treat them?

Answer 8

-Hookworm, Pinworm

-Treat with:
Thiabendazole
Mebendazole
Diethylcarbamazine
Pyrantel pamoate
Ivermectin

Question 9

How does infection of Trematodes (flukes) usually occur?

Answer 9

Contaminated water
-causes Schistosomiasis -> The second most important parasitic infection after malaria

Question 10

How are infections of Trematodes treated?

Answer 10

-praziquantel (tablet)

-MOA: Increases the cell permeability to calcium in schistosomes -> strong contraction of worm muscles and paralysis -> detachment of suckers
from the blood vessel walls

Question 11

How to treat Cestodes (Tapeworms)?

Answer 11

Praziquantel (tablet)

Question 12

Symptoms associated with Cestodes (Tapeworms)

Answer 12

-Weight-loss

-the worm consumes nutrients from the patient

Question 13

Which organisms are treated with Praziquantel?

Answer 13

-Trematodes (flatworms or flukes)
-Cestodes (tapeworms)

Question 14

Which organism causes Filariasis (Elephantiasis)?
Treatment
MOA

Answer 14

Nematode (roundworm)
-Treated with diethylcarbamazine
-disrupt arachidonic acid metabolism in susceptible worm

Question 15

Which disease is caused by uncooked pork?

Answer 15

Trichinosis (Roundworm, a nematode)

Question 16

What is the drug of choice for nematodes?

Answer 16

Mebendazole (Vermox)
-whipworm, pinworm, hookworm and
roundworm
-MOA – inhibits worm microtubule formation and
inhibits glucose uptake
-don’t take it with a high-fat meal (decreases absorption)

Question 17

Another drug to treat nematodes

Answer 17

Pyrantel pamoate
-poorly absorbed -> so it works well in the gut

Question 18

MOA for Pyrantel pamoate (PinX)

Answer 18

-By stimulating the release of acetylcholine,
inhibiting cholinesterase, and stimulating ganglionic
neurons

-depolarization in the helminth muscle
membrane -> paralysis

Question 19

What is onchocerciasis and how is it treated?

Answer 19

-River blindness

-Treated with Ivermectin

Question 20

MOA for Ivermectin

Answer 20

-broad-spectrum (kills many roundworms)
-Worm GABA agonist which paralyzes the worm

Question 21

Which drug should not be given with Ivermectin?

Answer 21

Benzodiapenes bc it also binds GABA receptors

-Should not be treated in patients with meningitis bc the inflammation may allow Ivermectin to cross the BBB -> sedation

Question 22

Other use of Ivermectin

Answer 22

-veterinary heartworm prophylaxis and treatment

-Collies may be extra-sensitive to the CNS effects due to the MDR1 gene -> multi-drug-resistant transporter which removes the drug
from the CNS