Antihelmintic drugs

Helminthiasis is a group of diseases (invasions), caused by parasitic worms. Parasitic worms in humans can be of two types: roundworms - Nemathelminthes (class Nematoda) and flatworms - Plathelminthes. The latter is divided into two classes: tapeworms (Cestoidea) and Trematoda.

The most common diseases caused by roundworms, are ascariasis, enterobiasis, trichocephalosis, strongyloidiasis, hookworm diseases (ankylostomiasis, necatoriasis). Diseases caused by tapeworms (beef tapeworm infection, pork tapeworm infection, diphyllobothriasis, hymenolepiasis) are widespread as well.

There are early (acute) and late (chronic) stages of helminthiasis. Pathogenesis of the early stage of the disease is determined by the toxic-allergic effect of metabolic products of larval forms of helminths, as well as endogenous factors of inflammation as a result of the invasion. Simultaneously with nonspecific inflammatory reaction develops an allergic reaction to antigens of helminths.

Acute helminthiasis usually develops within 2-4 weeks, rarely in 1-6 weeks after infection. It characterized by fever, skin rash of exudative or polymorphic nature, conjunctivitis, edema of the face, lesions of the upper respiratory tract, volatile infiltrates in the lungs, and sometimes diarrhea; in children - sore throat, lymphadenopathy, in extensive invasions occur focal pneumonia, pleuropneumonia, bronchospasm, myocarditis, hepatitis, violations of central nervous system (meningoencephalitis, sometimes - thrombosis of cerebral vessels). Depending on the severity of the disease in the absence of specific treatment, the clinical symptoms of acute phase last from 1 week up to 2-4 months, then the disease passes into the chronic stage.

The clinical picture of the chronic stage of helminthiasis is determined by species characteristics of the specific helminth. In helminthiases with a reproduction of larvae (strongyloidiasis, filariasis) persist allergic manifestations. They are also always present in larval invasion (toxocariasis, larval lung fluke disease, larva migrans visceralis, larva migrans cutanea). In the absence of larval forms, the clinical picture depends on the localization, size, number of helminth individuals.

The peculiarity of most helminthic diseases is their chronic course due to prolonged presence of the causative agent in the body and repeated reinfection. Chronic helminthic infections are accompanied by weakness, fatigue, irritability, sleep disturbances, dyspepsia, growth retardation (in children), reduced immune status.

Earlier in the treatment of helminthiasis mainly were used drugs based on herbals and plants - pumpkin seeds, tansy flowers, etc. Currently, however, there have been created and introduced into clinical practice new high-performance synthetic drugs classified as follows:

  1. Anthelminthics drugs with narrow spectrum of action
    1. anti-nematode infection medicines:
      • effective against roundworms - intestinal helminthiasis causative agents: bephenium hydroxynaphthoate, levamisole, pyrantel pamoat, piperazine adipinate, etc.
      • effective against roundworms - agents of extraintestinal helminthiasis - diethylcarbamazine citrate, ivermectin
    2. anti- cestoidea medicines:
      • effective against flatworms - intestinal helminthiasis causative agents - Niclosamide
      • effective against flatworms - agents of extraintestinal helminthiasis - Albendazole
    3. anti-distomiasis medicines:
      • effective against flukes - intestinal helminthiasis causative agents - Perchloroethylene
      • effective against flukes - agents of extraintestinal helminthiasis - bithionol, chloxylum
  2. Anthelminthic medicines with broad spectrum of action - albendazole, mebendazole, praziquantel

Anthelmintic preparations belong to etiotropic medicines. The mechanism of action of most anthelmintic drugs involves violation of neuromuscular transmission and metabolic processes in worms.

Efficacy and safety of anthelminthics requires strict compliance with several requirements: dosing, special diet, receiving laxatives, following certain regimens. Typically, dosage and method of administration of the same antihelminthic drug may vary depending on the type of helminthiasis. © 2020