1. Clinical Overview
Albendazole is a broad-spectrum benzimidazole anthelmintic agent. It is a prodrug whose active metabolite, albendazole sulfoxide, exerts its vermicidal effect by selectively and irreversibly inhibiting microtubule polymerization in parasitic cells, leading to impaired glucose uptake and depletion of energy stores, ultimately causing parasite death. It is a first-line agent for numerous intestinal and tissue helminth infections in India.
| Onset | Duration | Bioavailability |
|---|---|---|
| Parasite death begins within 24-48 hours, but clinical symptom resolution may take several days. | The anthelmintic effect is prolonged. A single 400mg dose is often sufficient for many intestinal worms. For systemic infections like neurocysticercosis, effects persist throughout the treatment course (8-30 days). | Poor (<5%) when taken on an empty stomach. Increases significantly (up to 5-fold) when co-administered with a fatty meal. |
2. Mechanism of Action
Albendazole is a prodrug. Its active metabolite, albendazole sulfoxide, binds with high affinity to beta-tubulin in parasitic cells, inhibiting its polymerization into microtubules. This disrupts vital cellular processes including intracellular transport, glucose uptake, and ATP production. The selective toxicity arises from the higher binding affinity to parasite tubulin compared to mammalian tubulin.
3. Indications & Uses
- Intestinal nematode infections: Ascariasis (Roundworm), Trichuriasis (Whipworm), Enterobiasis (Pinworm/Threadworm), Ancylostoma duodenale & Necator americanus (Hookworm)
- Neurocysticercosis (caused by larval stages of Taenia solium)
- Hydatid disease (caused by Echinococcus granulosus)
4. Dosage & Administration
Adult Dosage: Intestinal worms: Single oral dose of 400mg (two 200mg tablets). Often repeated after 2-4 weeks for pinworm. Neurocysticercosis: 400mg twice daily with meals for 8-30 days. Hydatid disease: 400mg twice daily with meals for 28-day cycles followed by a 14-day drug-free interval. Weight-based: 15 mg/kg/day (max 800mg) in divided doses.
Administration: Tablets must be taken ORALLY with water. For maximal absorption in systemic infections (neurocysticercosis, hydatid), administer WITH A FATTY MEAL (e.g., milk, butter, nuts). Tablets can be crushed or chewed if swallowing is difficult. For intestinal worms only, taking with food is less critical but still advised.
5. Side Effects
Common side effects may include:
- Headache
- Nausea
- Vomiting
- Abdominal pain
- Dizziness
- Reversible alopecia (hair loss)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Dexamethasone / Cimetidine / Praziquantel | Increases plasma concentration of albendazole sulfoxide by inhibiting CYP3A4 metabolism. | Moderate |
| Carbamazepine / Phenytoin / Phenobarbital / Rifampicin | Decreases plasma concentration of albendazole sulfoxide by inducing CYP3A4 metabolism, potentially reducing efficacy. | Significant |
| 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 (e.g., with milk, curd, or after a meal containing oil/ghee) for best results, especially if prescribed for a brain or liver worm infection.
- DO complete the full course of treatment as prescribed, even if you feel better.
- DO inform your doctor if you are pregnant, planning pregnancy, or breastfeeding.
- DO NOT take a double dose if you miss one. Take the next dose at the regular time.
- DO NOT share your medication with others, even if they have similar symptoms.
8. Toxicology & Storage
Overdose: Symptoms may include severe forms of common side effects: intense abdominal pain, nausea, vomiting, dizziness, headache, and lethargy. In massive overdose, bone marrow suppression or hepatotoxicity could occur.
Storage: Store below 30°C in a cool, dry place, protected from light and moisture. Keep the container tightly closed. Keep out of reach of children.