Anti-helminths Flashcards
How do Antihelminthic drugs enter the helminth and what is the MOA?
Drug must penetrate the cuticle (integument) of the worm or gain access to its alimentary tract,
Act by: Causing paralysis of worm and interfering with metabolism of worm
What is the MOA of mebendazole / albendazole (4)?
- Binds with β tubulin (microtubular protein) inhibiting polymerization and decreasing intracellular microtubules
- Blocks glucose uptake by parasite depleting parasite glycogen stores
- Inhibitis hatching of nematode eggs & their larvae
- Kills ova of Ascaris
*****Why is immobilization and lethal action on worms slow (2-3 days) with mebendazole?
The MOA of mebendazole ultimately results in locking the uptake of glucose and other nutrients, resulting in the gradual immobilization and eventual death of the helminths.
What anti-helminth drug for pinworms has an MOA of depolarizing neuromuscular blockade, increasing ACh release, and inhibiting cholinesterase stimulating the ganglia and causing spastic paralysis?
Pyrantel pamoate, oxantel pamoate
What anti-helminth drug for pinworms (second line) and roundworms has an MOA of GABA agonistic action of worm in which opening of chloride channels causes flaccid paralysis of worm?
Piperazine
What two anti-helminth drugs are for vet use and have an MOA of
stimulating a ganglia of worms and causing tonic paralysis & expulsion of worm?
Tetramisole & Levamisole
What is the DOC of Filariasis (Brugia malayi, W. Bancrofti) and Loa Loa and what is its MOA?
Diethylcarbamazine citrate (DEC), Arachidonic acid inhibitor in microfilaria altering its membranes and making it susceptible to phagocytosis by host cells. Affects muscular activity of microfilaria and adult worms & worms get dislodged.
What is the only effective oral drug to treat Strongyloides, Onchocerca volvulus, lymphatic filariasis (W. bancrofti), pediculosis and scabies?
Ivermectin
What is the MOA of Ivermectin?
Binds with high affinity to glutamate-gated chloride channels
increasing the permeability of the cell membrane to chloride ions with hyperpolarization of the nerve or muscle cell causing paralysis.
What drug can be used on tapeworms (i.e. cestodes / flatworms) except for T. solium?
Niclosamide
Why is Niclosamide not recommended for T. solium?
Damaged T.solium worms: release larvae causing cysticercosis
What is the MOA of Niclosamide?
Inhibits oxphos and interferes with ATP generation causing decreased glucose uptake, injury, and digestion of the worm.
What anti-helminth drug is effective against cestodes & trematodes
and what is its MOA?
Praziquantel, increases cell membrane permeability to calcium in schistosomes causing contraction paralysis and dislodging while in cestodes inhibit adenosine uptake
What are mebendazole / albendazole used for?
Nematodes (Ascaris), hookworm (albendazole), pinworm, trichuris (mebendazole 3 days, second line albendazole 3 days), trichinella (albendazole, second line mebendazole), Cestodes (Hydatid disease –Echinococcus, Neurocysticerosis)
What are Pyrantel pamoate, oxantel pamoate used for?
Ascaris (pyrantel), Pinworm (pyrantel, repeat after 2 wks.), hookworm
