1. Clinical Overview
Albendazole is a broad-spectrum benzimidazole anthelmintic agent. It is a prodrug whose active metabolite, albendazole sulfoxide, exerts its anthelmintic effect by selectively and irreversibly inhibiting tubulin polymerization in parasitic cells, leading to depletion of energy (ATP) and immobilization. It is a first-line agent for neurocysticercosis and hydatid disease in India and is widely used in mass drug administration (MDA) programs for soil-transmitted helminthiasis.
| Onset | Duration | Bioavailability |
|---|---|---|
| Parasite immobilization begins within hours; clinical symptom resolution may take days to weeks depending on infection. | The anthelmintic effect is prolonged due to its mechanism. Dosing intervals are typically once daily or as a single dose for intestinal worms. | Approximately 5% for the parent drug when taken orally on an empty stomach. Bioavailability increases up to 3-fold (approx. 15-20%) when co-administered with a fatty meal. |
2. Mechanism of Action
Albendazole is a prodrug. Its active metabolite, albendazole sulfoxide, binds selectively and with high affinity to parasite beta-tubulin, inhibiting its polymerization into microtubules. This disrupts cytoplasmic microtubules in intestinal and larval stages of susceptible helminths.
3. Indications & Uses
- Neurocysticercosis (caused by Taenia solium)
- Hydatid disease (caused by Echinococcus granulosus)
- Intestinal nematode infections: Ascariasis (roundworm), Trichuriasis (whipworm), Enterobiasis (pinworm), Ancylostomiasis (hookworm - Necator americanus & Ancylostoma duodenale)
- Strongyloidiasis (off-label, but commonly used)
4. Dosage & Administration
Adult Dosage: Intestinal Helminths: 400mg as a single oral dose (often repeated after 2-4 weeks for some worms). Hydatid Disease: 400mg twice daily with meals for 28 days, repeated for 1-3 cycles with 14-day drug-free intervals. Neurocysticercosis: 400mg twice daily with meals for 8-30 days (as per cyst resolution). Weight-based: 15 mg/kg/day (max 800mg) in two divided doses.
Administration: Tablet must be taken orally, swallowed whole with water. For systemic infections (hydatid, neurocysticercosis), MUST be taken WITH A FATTY MEAL (e.g., milk, butter, nuts) to enhance absorption. For intestinal worms, can be taken with or without food. Dosage cycles must be completed as prescribed.
5. Side Effects
Common side effects may include:
- Headache
- Nausea, vomiting, abdominal pain
- Dizziness, vertigo
- Transient elevation of liver enzymes (AST, ALT)
- Reversible alopecia (hair loss) with long-term use
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Dexamethasone / Cimetidine / Praziquantel | Increases plasma levels of albendazole sulfoxide by inhibiting CYP3A4 metabolism, potentially increasing efficacy and toxicity. | Moderate |
| Carbamazepine / Phenytoin / Phenobarbital | Decreases plasma levels of albendazole sulfoxide by inducing CYP3A4 metabolism, potentially reducing efficacy. | Moderate |
| Theophylline | Albendazole may increase Theophylline levels; monitor for toxicity. | Moderate |
| Warfarin | Potential interaction; monitor INR closely as albendazole may affect coagulation. | Moderate |
7. Patient Counselling
- DO take the tablet with a fatty meal (like milk or nuts) if prescribed for tapeworm/cyst infections.
- DO complete the full course of treatment even if you feel better.
- DO practice good hygiene (wash hands, trim nails) to prevent reinfection, especially for pinworms.
- DO inform your doctor if you are pregnant, planning pregnancy, or breastfeeding.
- DONT take a double dose to make up for a missed one.
- DONT share your medication with others.
8. Toxicology & Storage
Overdose: Symptoms may include severe forms of common side effects: intense abdominal pain, nausea, vomiting, headache, dizziness, lethargy, and potentially hepatotoxicity or bone marrow suppression.
Storage: Store below 30°C in a cool, dry place, protected from light and moisture. Keep out of reach of children.