Benzimidazole anthelmintics

Benzimidazoles bind β-tubulin in worm cells, at its colchicine-sensitive site, and stop it polymerizing into microtubules. Without microtubules the worm's intestinal cells cannot take up glucose, glycogen stores run down, ATP runs short, and the worm is immobilized and dies. Mebendazole stays mostly in the gut; albendazole is poorly absorbed too, but its active sulfoxide metabolite reaches tissue cysts.

• AlbendazoleIts active sulfoxide reaches tissue cysts, so albendazole, unlike mebendazole, treats tapeworm larvae in the brain and liver. WHO gives it in mass treatment of school-age children.
• MebendazoleActs almost only in the gut, which suits intestinal worms; for tapeworm cysts in tissues, albendazole is used instead. WHO lists both for mass deworming.

• Roundworm, hookworm, whipworm and threadworm
• Neurocysticercosis and hydatid disease (albendazole)
• Lymphatic filariasis, with ivermectin or DEC

• Raised liver enzymes, rarely hepatitisKnown forSerious
• Bone marrow suppression and agranulocytosisKnown forSerious
• Abdominal pain and discomfort
• Nausea and vomiting
• Diarrhea
• Headache and dizziness
• Reversible hair loss
• SeizuresSerious
• Rash and other allergic reactions
• Harm to the fetus (seen in animal studies)Serious

What the class has in common. Each drug's card has its own, and Known for marks what an exam expects you to know.

• Long albendazole courses need blood counts and liver tests at the start of each cycle and every 2 weeks.
• Albendazole may harm the fetus, so pregnancy is ruled out first; mebendazole is used in pregnancy only if benefits outweigh risks.
• In neurocysticercosis, dying cysts can cause seizures and raised brain pressure, so steroids and anticonvulsants are given.
• Avoid mebendazole with metronidazole, a combination linked to SJS and TEN.

Written for biofideX in plain words, after checking these references:

• Albendazole tablets: label (DailyMed)
• Mebendazole chewable tablet: label (DailyMed)
• Albendazole (NCI Thesaurus)
• Mebendazole (NHS)
• Soil-transmitted helminth infections (WHO)
• Lymphatic filariasis (WHO)

For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.