albendazole
Benzimidazole anthelmintic· Brands: Albenza, Zentel, Eskazole, ValbazenPOTOP
Mechanism of action
Albendazole is a benzimidazole carbamate that acts on the helminth cytoskeleton. It binds with high affinity to beta-tubulin and prevents its polymerisation into microtubules. Loss of microtubules blocks glucose uptake, transport of secretory vesicles and cell division, so the parasite is progressively depleted of energy and is killed or expelled. Selectivity comes from much greater binding affinity for helminth beta-tubulin than for human tubulin. Susceptibility varies with the organism and its lifecycle stage: adult intestinal nematodes respond well to short courses, while tissue-dwelling larvae and cestode cysts need prolonged exposure and a higher total dose. Albendazole behaves largely as a prodrug; the systemic metabolite albendazole sulfoxide carries most of the activity against tissue helminths.
Pharmacokinetics
Absorption after oral doses is slow and variable because the drug is poorly water soluble; a fatty meal can raise systemic exposure to the active metabolite several-fold, which matters when treating tissue infections. Extensive first-pass hepatic metabolism by CYP3A4 produces albendazole sulfoxide, the active metabolite, which is then oxidised to the inactive sulfone. Sulfoxide is about 70 per cent protein bound, distributes widely including into cerebrospinal fluid, hydatid cyst fluid and bile, and has a plasma half-life of roughly 8 to 12 hours. Elimination is mainly biliary with some renal excretion. Co-administration of dexamethasone or praziquantel can raise sulfoxide concentrations, whereas rifampicin, phenytoin or carbamazepine can lower them; check a current formulary for interactions.
Indications & dosing
Intestinal nematode infections (ascariasis, hookworm, trichuriasis)
For children over 2 years. For children aged 12 to 24 months, use 200 mg as a single dose. Take with food.
- adult · PO: 400 mg single dose · For children over 2 years. For children aged 12 to 24 months, use 200 mg as a single dose. Take with food.
Intestinal nematode infections in children aged 12 to 24 months
Not recommended for children under 12 months. Take with food.
- pediatric · PO: 200 mg single dose · Not recommended for children under 12 months. Take with food.
Hydatid disease (echinococcosis)
Take with food. Treat for 28 days then repeat after 14 days off. Monitor liver enzymes and full blood count.
- adult · PO: 15 mg/kg/day divided twice daily · Take with food. Treat for 28 days then repeat after 14 days off. Monitor liver enzymes and full blood count.
Neurocysticercosis
Give with corticosteroids and anticonvulsants as indicated. Duration 8 to 30 days depending on lesion.
- adult · PO: 15 mg/kg/day divided twice daily · Give with corticosteroids and anticonvulsants as indicated. Duration 8 to 30 days depending on lesion.
Cutaneous larva migrans
Continue for 3 days. Take with food.
- adult · PO: 400 mg daily · Continue for 3 days. Take with food.
Giardiasisoff-label
For 5 days. May be used when other agents are unsuitable; practice varies by region.
- adult · PO: 400 mg daily · For 5 days. May be used when other agents are unsuitable; practice varies by region.
Strongyloidiasis
For 3 days. Alternative to ivermectin.
- adult · PO: 400 mg daily · For 3 days. Alternative to ivermectin.
Trichinellosis
For 8 to 14 days. Take with food.
- adult · PO: 400 mg twice daily · For 8 to 14 days. Take with food.
Contraindications & precautions
- Known hypersensitivity to albendazole or other benzimidazoles · Cross-reactivity within the benzimidazole class is recognised. Avoid rechallenge if a previous reaction occurred.
- Pregnancy, particularly the first trimester · Teratogenic in animal studies. Single-dose deworming is generally deferred until after pregnancy; high-dose therapy for hydatid disease or neurocysticercosis may still be justified if benefit outweighs risk. Check local labelling, as advice differs by indication and region.
- Ocular cysticercosis or retinal involvement · Drug-induced death of cysts in the eye may cause irreversible retinal or intraocular damage. Specialist assessment and imaging before treatment are essential.
- Severe hepatic impairment or cirrhosis · Albendazole is metabolised in the liver and hepatic impairment increases drug exposure. Use with caution, reduce dose where advised, and monitor liver function closely.
- Mass deworming in children under 12 months · Safety data are limited and chewable tablets pose a choking risk in infants. Programme guidance excludes this age group; treat individual cases only on specialist advice.
- For systemic infections (hydatid disease, neurocysticercosis, tissue helminths) give with a fatty meal to improve absorption; for intestinal worms this matters less because the effect is intraluminal.
- Before and during prolonged high-dose therapy, check full blood count and liver enzymes at baseline and roughly every two weeks; stop treatment if counts fall significantly or transaminases rise markedly.
- In neurocysticercosis, co-prescribe corticosteroids and anticonvulsants as directed, and monitor for raised intracranial pressure caused by the inflammatory response to dying cysts.
- In hydatid disease, treatment carries a risk of cyst rupture and anaphylaxis; manage jointly with surgical or interventional radiology services and follow specialist protocols.
- Advise women of childbearing potential to avoid pregnancy during and shortly after treatment; exclude pregnancy first where practical and follow local labelling on contraception duration.
- For intestinal nematodes, confirm cure with repeat stool microscopy after treatment, treat household contacts where indicated, and reinforce hand hygiene, footwear and food safety to reduce reinfection.
Adverse effects
- Abdominal pain, nausea, vomiting
- Headache
- Dizziness
- Fever and worsening neurological symptoms during treatment of neurocysticercosis (inflammatory reaction to dying cysts)serious
- Raised intracranial pressure or seizures during neurocysticercosis therapyserious
- Raised liver enzymes, drug-induced hepatitisserious
- Reversible alopecia and mild hair loss
- Bone marrow suppression: neutropenia, thrombocytopenia, pancytopenia, agranulocytosisserious
- Rash, urticaria, pruritus
- Stevens-Johnson syndrome, toxic epidermal necrolysisserious
Monitoring, pregnancy & toxicity
- Full blood count, including white cell count and platelets · Before treatment and periodically during prolonged high-dose therapy (e.g. weekly or as clinically indicated).
- Liver function tests, including transaminases and bilirubin · Before treatment and periodically during prolonged high-dose therapy.
- Pregnancy test in women of childbearing potential · Before starting treatment for systemic infections.
- Clinical response and imaging for tissue helminth infections · During and after treatment, as clinically indicated.
- Neurological status for neurocysticercosis, including seizures and signs of raised intracranial pressure · During treatment, especially in the first weeks.
- Pregnancy: Avoid albendazole in pregnancy, especially in the first trimester, unless the infection is life-threatening or there is no safer alternative. For intestinal infections, delay treatment until after delivery or use an alternative. For systemic infections such as neurocysticercosis or echinococcosis, treat if the benefits outweigh the risks, with specialist advice. Effective contraception is advised for women of childbearing potential during treatment.
- Toxicity: Gastrointestinal upset: nausea, vomiting, diarrhoea, abdominal pain. These are usually mild and transient. · Supportive care. Taking the dose with food may reduce symptoms. Usually no specific treatment is needed.
- Toxicity: Hepatotoxicity: raised transaminases, jaundice or hepatitis. Risk is greater with prolonged high-dose therapy. · Stop albendazole, monitor liver function tests, and provide supportive care. Seek specialist advice for severe cases.
- Toxicity: Haematological toxicity: leukopenia, thrombocytopenia or pancytopenia, especially with prolonged high-dose therapy. · Stop the drug, check full blood count, and manage supportively. Consider haematology input if blood counts are significantly reduced.
- Toxicity: Overdose: nausea, vomiting, dizziness and headache. There is no specific antidote. Rarely, severe hepatic or bone marrow toxicity may occur. · Provide supportive and symptomatic care. Activated charcoal may be considered if ingestion was recent. Monitor liver function tests and full blood count.
Clinical notes
Albendazole treats intestinal nematodes such as ascariasis, hookworm infection, trichuriasis, enterobiasis and strongyloidiasis, and tissue helminths including hydatid disease, neurocysticercosis, trichinellosis and cutaneous larva migrans; it is also used as an alternative in giardiasis. Regimens vary widely, from single doses for intestinal worms in preventive chemotherapy programmes to repeated or prolonged courses taken with food for tissue disease. Common adverse effects are abdominal discomfort, nausea, headache and dizziness, and transient rises in liver enzymes are frequent with prolonged courses. Rare but serious effects include hepatitis, cholestatic jaundice and bone marrow suppression, so blood counts and liver enzymes are monitored during long treatment. Corticosteroids and anticonvulsants may be needed in neurocysticercosis to control inflammation and seizures. Avoid in pregnancy, particularly the first trimester, and in severe hepatic impairment unless benefit clearly justifies it. Age limits, dosing and monitoring practice vary by country and formulary, so verify locally.
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BNF; WHO Model Formulary; national formulary or SmPC; local antimicrobial and antiparasitic guidelines