Anti-Helminth Drugs
anti-helminth drugs
Agents with neuromuscular targets
These drugs paralyze the worms, rendering them incapable of attaching to or moving through the host.
Albendazole, Mebendazole, and Thiabendazole:
Inhibit microtubule formation.
Broad spectrum activity for intestinal nematode infections:
Ascaris lumbricoides
Necator americanus
Enterobius vermicularis
Strongyloides stercoralis
Trichuris trichiura
Ancyclostoma (the cause of cutaneous larva migrans)
Trichinella spiralis
Two cestodes infections:
Taenia solium*, the cause of neurocysticercosis
Echinococcus*, which causes hydatid disease.
Adverse effects are minimal, though some authors report that thiabendazole is the least used of the three drugs due to side effects.
Pyrantel pamoate:
Depolarizes nematode neuromuscular junctions.
Used as treatment in some intestinal nematode infections:
Ascaris lumbricoides
Necator americanus
Enterobius vermicularis
Adverse effects include gastrointestinal upset, headache, and rash, all of which tend to be transient.
Praziquantel:
Increases calcium permeability in parasite cells.
Treats trematode infections, including:
Schistosomes
Paragonimus
Chlonorchis
It is also used to treat cestodes infections, including:
Taenia solium
Hymenolepis
Adverse effects include diarrhea and abdominal pain, as well as fever and lethargy.
Be aware that symptoms of schistosomiasis can be exacerbated.
Ivermectin:
Multiple mechanisms of action: it alters the chloride ion permeability of parasite cells, which leads to paralysis, and it is thought to be a GABA agonist. Furthermore, it kills microfilariae and impairs filariae reproduction.
Treats some intestinal nematode infections caused by Ascaris lumbricoides, Enterobius vermicularis,
Strongyloides stercoralis, and Trichuris trichiura.
It is also the first choice of treatment for the filarial nematode Onchocerca volvulus, which causes River blindness.
Adverse effects can occur in response to Onchocerca volvulus microfilariae death: the Mazzotti reaction, which is a severe inflammatory response to the dead parasites, is characterized by fever, chills, swollen lymph nodes, arthralgias, and other symptoms.
Diethylcarbamazine (aka, DEC):
Promotes phagocytosis of microfilariae.
Used to treat filarial nematode infections, including Wuchereria bancrofti and Brugia malayi, Loa loa and is an alternative treatment for Onchocerca volvulus infections.
Also used to treat infections caused by Toxocara nematodes, which cause visceral larva migrans.
As previously indicated, death of Onchocerca volvulus can produce the Mazzoti reaction; this drug has also been associated with damaging inflammation in the eye.
Use caution when treating patients with high levels of circulating Loa loa microfilariae, because this drug can produce serious adverse effects, including fatal encephalopathy, when the microfilariae load is high.
Niclosamide:
Blocks oxidative phosphorylation.
Alternative treatment for cestode infections.
Adverse effects include transient gastrointestinal symptoms.