ANTHELMINTICS Flashcards
Capability of ridding the body of parasitic worms or helminths
Anthelmintics
2 phyla and helminths parasitic to humans & animals are:
Platyhelminthes
- Cestodes (tapeworms)
-Trematodes (Flukes)
Nenathelminths
-Nematodes or true roundworms
-Hexahydropyrazine or diethylenediamine
-Treatment of pinworm (Enterobius [Oxyuris] vermicularis) & roundworm
(Ascaris lumbricoides) infestations
Piperazine (Arthriticine®, Dispermin®)
Blocks response of ascaris muscle to acetycholine causing flaccid
paralysis in the worm w/c is dislodged from intestinal wall & expelled in
feces
Piperazine
-Highly water-soluble crystalline compound that has selective anthelmintic
activity
-Effective against various forms of filariasis, including Bancroft,
onchocerciasis & laviasis
-Active against ascariasis
Diethylcarbamazepine Citrate (Hetrazan®
-Depolarizing neuromuscular blocking agent that causes spastic paralysis
in susceptible helminths
-Treatment of infestations caused by pinworms & roundworms
-Because its action opposes that of piperazine, it should not be used
together
-A/E: gastrointestinal effects
Pyrantel Pamoate (Antiminth®)
-Forms complexes with metal ions
-Inhibits helminth-specific enzyme fumarate reductase
-Broad-spectrum anthelmintic activity
-Treat enterobiasis, strongyloidiasis (threadowrm infection), ascariasis,
uncinariasis (hookworm infection), & trichuriasis (whipmworm infection)
-Used to relieve symptoms associated w/ cutaneous larva migrans (creeping
eruption) & invasive phase of trichinosis
-Widely used in veterinary practice to control intestinal helminths in livestock
Thiabendazole
-Broad-spectrum anthelmintic, effective against nematode infestations
(whipworm, pinworm, roundworm, hookworm)
-Does not affect glucose metabolism in the host
-Also inhibits cell division in nematodes
-Poorly absorbed by oral route
-Teratogenic in lab animals, thus should not be given during pregnancy
Mebendazole
-Broad-spectrum anthelmintic
-Widely used for treatment of intestinal nematode infection
-Effective as single-dose treatment for ascariasis, new and old world
hookworm infections, & trichuriasis
-Multiple-dose therapy w/ albendazole can eradicate pinworm,
threadworm, capillariasis, clonorchiasis & hydatid disease
-Its effectiveness against tapeworms is generally more variable, & less
impressive
Albendazole
-Oral absorption enhanced by fatty meal
-Drug undergoes rapid & extensive first-pass metabolism to the sulfoxide,
w/c is the active form in plasma
-Well tolerated in single-dose therapy for intestinal nematodes
-High-dose, prolonged therapy for clonorchiasis or echinococcal disease:
-A/E: bone marrow depression, elevation of hepatic enzymes, & alopecia
Albendazole
-Potent taeniacide that causes rapid disintegration of worm segments &
the scolex
-Well tolerated following oral administration, & little or no systemic
absorption of it occurs
-Saline purge 1 to 2 hrs after ingestion of taeniacide is recommended to
remove damaged scolex & worm segments
-Procedure is mandatory in the tx of pork tapeworm infestation to
prevent possible cysticercosis resulting from release of live ova from
worm segments damaged by drug
Niclosamide
-Chlorinated bisphenol, formerly used in soaps, & cosmetics for its
antimicrobial properties but was removed from market for topical use
because of reports of contact photodermatitis
-Useful anthelmintic properties; used as fasciolicide & taeniacide
-Agent of choice for tx of infestations caused by liver fluke Fasciola
hepatica & the lung fluke Paragonimus westermani
-Niclosamide is superior to it for tx of tapeworm infestations
Bithionol
-Antischistosomal agent indicated for tx of Schistosoma mansoni (intestinal
schistosomiasis)
-Inhibit DNA, RNA & protein synthesis in schistosomes
-Good oral bioavailability
-It is extensively metabolized to inactive metabolites, principal one is 6-
carboxy derivative
-Available in capsules containing 250mg of the drug
-S/E: dizziness & drowsiness
- Serious reactions but rare: epileptiform convulsions
Oxamniquine
-Broad-spectrum agent effective against various trematodes
-Agent of choice for treatment of infections caused by schistosomes (blood
flukes)
-Effective treatment for fasciolopsiasis (intestinal fluke), clonorchiasis
(chinese liver fluke), fascioliasis (sheep liver fluke), opisthorchosis (liver
fluke) & paragonimiasis (lung fluke)
-Increases cell membrane permeability of susceptible worms, resulting in
the loss of extracellular calcium
- Available as 600mg film-coated tablets
Praziquantel (Biltricide®)
