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[Pharmacology](https://durgical.com/en/pharmacology/) · Class

# Anthelmintics

Drugs against worms: benzimidazoles for roundworms and cysts, ivermectin for Strongyloides and filariae, praziquantel for flukes and tapeworms.

Updated 2026-11-01

## What they are

Drugs against helminths: nematodes (roundworms), cestodes (tapeworms and their cysts) and trematodes (flukes). WHO uses albendazole or mebendazole for mass deworming of children and women where soil-transmitted helminths are common, as in rural Colombia.

## Mechanism of action

Three key targets: benzimidazoles (albendazole, mebendazole) bind worm β-tubulin and block microtubules; ivermectin opens glutamate-gated chloride channels and leaves the worm in flaccid paralysis; praziquantel lets calcium in, causing spastic paralysis and damaging the tegument of flukes and tapeworms. Pyrantel is a nicotinic agonist that causes spastic paralysis.

Target: β-tubulin, glutamate-gated chloride channels, schistosome TRP channel

## Key points

- Soil-transmitted helminths (Ascaris, Trichuris, hookworms): albendazole or mebendazole; Strongyloides responds poorly to them: ivermectin.
- Neurocysticercosis: albendazole (better CSF penetration) with a corticosteroid; praziquantel is added when there are several viable cysts.
- The retina is examined before treating neurocysticercosis; intraventricular cysts usually go to surgery.
- Ivermectin: Mazzotti reaction in onchocerciasis and severe encephalopathy with heavy Loa loa microfilaraemia.
- Praziquantel: schistosomiasis and tapeworms; contraindicated in ocular cysticercosis and with rifampicin; Fasciola hepatica is treated with triclabendazole.

## Drugs in this class

- [**Albendazole** Broad-spectrum benzimidazole: used for deworming against soil-transmitted helminths and, absorbed with fatty food, for… Helminth β-tubulin (colchicine site)](https://durgical.com/en/pharmacology/albendazole/)
- [**Mebendazole** A benzimidazole that is barely absorbed: it acts in the gut lumen against roundworm, whipworm, hookworm and pinworm. Helminth β-tubulin (colchicine site)](https://durgical.com/en/pharmacology/mebendazole/)
- [**Ivermectin** Single-dose oral avermectin: the drug of choice for strongyloidiasis and onchocerciasis; it opens chloride channels… Nematode glutamate-gated chloride channel (GluCl)](https://durgical.com/en/pharmacology/ivermectin/)
- [**Praziquantel** Anthelmintic against flukes and tapeworms: the drug of choice for schistosomiasis; it lets calcium in and paralyses… Schistosome TRPM channel (TRPM_PZQ)](https://durgical.com/en/pharmacology/praziquantel/)

## Others in the class

- Diethylcarbamazine
- Pyrantel pamoate
- Levamisole
- Niclosamide
- Triclabendazole
- Moxidectin

## Test yourself

Think of the answer, then tap the question to see it.

## Which anthelmintic is preferred for Strongyloides stercoralis?

Ivermectin; Strongyloides responds poorly to albendazole and mebendazole.

## Why is albendazole preferred over praziquantel in neurocysticercosis?

It penetrates the CSF better, and the corticosteroids given with it raise its levels while they lower praziquantel levels.

## What target do benzimidazoles act on?

Worm β-tubulin: they stop microtubules from forming.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Soil-transmitted helminth infections](https://www.who.int/news-room/fact-sheets/detail/soil-transmitted-helminth-infections) (World Health Organization, 2023); [Clinical Care of Cysticercosis](https://www.cdc.gov/cysticercosis/hcp/clinical-care/index.html) (Centers for Disease Control and Prevention (CDC), 2024); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=P02) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 68 (McGraw Hill, 2023).

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