Anthelmintic Agents

Anthelmintic agents are compounds that act against the effect of parasitic worms. These worms are called helminths. The helminths include flatworms, like tapeworms (cestodes) and flukes(trematodes), roundworms (nematodes), etc. They cause infections in human beings and domestic animals as well. The infection caused by the helminths is called helminthiasis. This contamination occurs through soil and water and attacks the intestine; hence, they are called intestinal worms. One of the most used anthelmintic agents is benzimidazole.

Based on these worms, the anthelmintic agents can be categorised as cestode anthelmintic, nematode anthelmintic, and trematode anthelmintic.

How do Anthelmintic Agents Work?

Anthelmintic agents are also known by other names, such as vermicides that kill the helminth inside the intestine, and vermifuges that expel the worms out of the intestine by peristaltic movement. Examples of vermifuges are mebendazole and ivermectin.

Most of these anthelmintic agents obstruct the worm’s glucose absorption inside the intestine, causing paralysis of the parasite. Others bind to the nerves and muscle cells resulting in the parasite’s death. Some inhibit the reproduction of young parasites from their parents.

Type of Anthelmintic Agents

The type of anthelmintic agents depends upon the infection caused by a particular helminth and the severity of the infection. These are generally taken orally and are used for both humans and animals. Some of the commonly used anthelmintic agents are discussed below.

Benzimidazole

Researchers say that these compounds display several biochemical effects. Benzimidazole is a very effective anthelmintic agent due to its capacity to deal with the cytoskeleton through a reaction with β-tubulin. The benzimidazole affects the worms in various ways impairing locomotion, inhibiting reproduction, and other detrimental impacts on oocytes.

Praziquantel

Praziquantel is used to treat cestode and trematode infections caused by flukes and tapeworms. This is easily absorbed by the intestinal tract and produces tetanus-like contractions in the worm’s muscle, and leads to spasticity destroying its membranes. This increases the defence system of the host.

Albendazole

Albendazole is a benzimidazole. It is a benzimidazole carbamate. It is structurally similar to mebendazole. It has an imidazole ring in its structure. Albendazole is primarily used to treat cestode helminthic infections such as tapeworms. This agent inhibits the glucose uptake of the parasite, leading to the worm’s death.

Quinacrine

Quinacrine is an animal anthelmintic agent. It mostly works on tapeworm infections in cattle, dogs, and other animals. This agent is also used for treating malaria.

Ivermectin

Ivermectin invokes a persistent and potential paralysis of nematodes. Nematodes, like filarial worms, reside in the blood or lymphatics, etc. The treatment requires these anthelmintic agents to penetrate through tissues and kill the worms. Ivermectin reaches blood level very quickly and acts against filariae. The death of these worms can cause an allergic reaction in the patient.

Other anthelmintic agents used for the same treatment include Diethylcarbamazine, etc.

Mebendazole 

Mebendazole is a benzimidazole. It has a similar structure and function as albendazole. It contains an imidazole ring in its molecular structure. Being a vermicide, mebendazole is used to treat large intestinal whipworms, pinworms, and roundworms. Like albendazole, it also interferes with the glucose intake of the worm and paralyses the parasite to death.

Piperazine

Piperazine is the anthelmintic agent used for both human and veterinary medicine. Piperazine is used in the treatment of nematodes. These agents loosen the worms and force them out of the human or domestic animal’s body through excretion.

Thiabendazole

Thiabendazole is structurally similar to albendazole and mebendazole. This is the first of the Benzimidazole class. Thiabendazole is primarily used to treat various nematode infections in cattle, sheep, horses, etc.

Pyrantel Pamoate and Levamisole

These are kinds of anthelmintic agents that evoke the spastic paralysis of muscles. These cause death of the worms. These agents are not completely absorbed by the intestinal wall of the receptor, and hence, leave residual as lumens. Along with treating pinworms, these can be used as an alternative for hookworms, trichostrongyliasis, and Ascaris. 

Hygromycin

Hygromycin is primarily an antibiotic. This is used for animals like swine or poultry. This is not a direct anthelmintic agent, yet can be used as a feed additive to eradicate nodular worms, whipworms, cecal worms, etc.

Apart from the aforementioned anthelmintic agents, other anthelmintics like Dithiazanine are used to treat infections caused by parasitic worms living in the intestines of human beings and cattle. This veterinary anthelmintic agent is used for animals to cure nematode infections of threadworms and heartworms. Next on the list is Phenothiazine, which is used against wireworms (Haemonchus contortus) in cattle and sheep.

Some other names of anthelmintic agents include Vermox, Stromectol, Moxidectin, Egaten, Emverm, Albenza, Biltricide, etc.

Conclusion

Anthelmintic agents treat diseases caused by worms, mostly cestodes, nematodes, trematodes, etc. These include tapeworms, flukes, heartworms, roundworms, filaria, etc. The way of action to kill or eliminate these worms is mostly to inhibit their growth and production by obstructing glucose intake and causing spasticity. The idea is to either kill them or push them out of the host’s intestinal tract. 

These anthelmintic agents are not only used against these helminths but can also be used as a treatment for other diseases like Ascaris, Malaria, etc. Hence, the production and utilisation of these agents should be spread as much as possible to cure people and animals of the infections.