Albendazole: Broad-Spectrum Anthelmintic for Effective Parasite Elimination
Albendazole is a benzimidazole carbamate anthelmintic agent with broad-spectrum activity against intestinal and tissue-dwelling nematodes and cestodes. This synthetic compound demonstrates vermicidal and ovicidal properties through selective inhibition of parasite-specific tubulin polymerization, disrupting microtubule formation and energy metabolism. Its extensive first-pass metabolism produces the active sulfoxide metabolite, which achieves therapeutic concentrations in various tissues, including cysts, making it particularly valuable for systemic parasitic infections. The medication represents a cornerstone in antiparasitic therapy due to its excellent tissue penetration and proven efficacy across multiple parasitic indications.
Features
- Chemical name: methyl 5-(propylthio)-2-benzimidazolecarbamate
- Molecular formula: C₁₂H₁₅N₃O₂S
- White to off-white crystalline powder
- Poor aqueous solubility (0.2 mg/mL at 25°C)
- Lipophilic properties enabling tissue penetration
- Metabolized to active albendazole sulfoxide
- Plasma protein binding approximately 70%
- Elimination half-life of 8-12 hours for active metabolite
- Available in 200mg and 400mg tablet formulations
- Chewable tablets available for pediatric administration
Benefits
- Comprehensive Parasite Coverage: Effective against both adult parasites and developing larvae across multiple species
- Tissue Penetration Capability: Achieves therapeutic concentrations in cysts, central nervous system, and other tissues
- Single-Dose Efficacy: For many intestinal parasites, a single dose provides complete eradication
- Preventive Capability: Regular administration in endemic areas reduces parasite burden and transmission
- Well-Tolerated Profile: Generally safe with manageable side effects in most patient populations
- Cost-Effective Treatment: Provides high cure rates at relatively low treatment cost
Common use
Albendazole is indicated for the treatment of various parasitic infections including neurocysticercosis caused by larval forms of Taenia solium, hydatid disease caused by larval forms of Echinococcus granulosus, pinworm infection (Enterobius vermicularis), roundworm infection (Ascaris lumbricoides), hookworm infection (Ancylostoma duodenale and Necator americanus), whipworm infection (Trichuris trichiura), and threadworm infection (Strongyloides stercoralis). It is also used off-label for other helminthic infections including cutaneous larva migrans, gnathostomiasis, and microsporidiosis. The World Health Organization recommends albendazole for mass drug administration programs in endemic areas for soil-transmitted helminthiases.
Dosage and direction
Dosage varies according to the type of infection and patient weight. For neurocysticercosis: 400mg twice daily with meals for 8-30 days. For hydatid disease: 400mg twice daily with meals for 28-day cycles followed by 14-day drug-free intervals, typically for 3 cycles. For intestinal parasites: single 400mg dose for adults and children over 2 years; 200mg for children 1-2 years. Administration with a fatty meal increases bioavailability by up to fivefold. Tablets should be swallowed whole with water, though chewable formulations are available. Dosage adjustments are necessary in patients with hepatic impairment. Treatment duration may require extension based on clinical response and parasite burden.
Precautions
Hepatic function should be monitored before and during treatment, with transaminase measurements at baseline and every 2 weeks during therapy. Complete blood counts should be performed regularly due to potential bone marrow suppression. Use with caution in patients with pre-existing liver disease or biliary obstruction. Corticosteroid therapy should be administered concurrently for neurocysticercosis to prevent inflammatory reactions to dying parasites. Effective contraception must be used during and for one month after treatment due to potential teratogenicity. Breastfeeding should be discontinued during therapy. Retinal examination is recommended in patients being treated for neurocysticercosis. Patients should be advised that dizziness may occur and to avoid driving or operating machinery if affected.
Contraindications
Hypersensitivity to albendazole, other benzimidazoles, or any component of the formulation. Pregnancy (category C) due to demonstrated embryotoxicity and teratogenicity in animal studies. Breastfeeding women should not use unless absolutely necessary. Patients with known bone marrow suppression or pre-existing pancytopenia. Severe hepatic impairment without appropriate monitoring capabilities. History of drug-induced agranulocytosis or aplastic anemia. Concomitant use with drugs that significantly inhibit cytochrome P450 enzymes may require contraindication based on risk assessment. Children under one year of age due to limited safety data.
Possible side effect
The most common adverse reactions include abdominal pain (6%), nausea (4.2%), vomiting (3.7%), headache (3.5%), and dizziness (1.7%). Less frequently reported effects include reversible alopecia (2.7%), elevated liver enzymes (16% in long-term therapy), leukopenia (1.3%), and thrombocytopenia (0.9%). Rare but serious side effects include Stevens-Johnson syndrome, toxic epidermal necrolysis, agranulocytosis, aplastic anemia, and hepatitis. Transient increases in intracranial pressure may occur in neurocysticercosis patients. Allergic reactions including rash, pruritus, and urticaria have been reported in approximately 1% of patients. Gastrointestinal disturbances are typically mild and self-limiting.
Drug interaction
Albendazole metabolism involves cytochrome P450 1A2 and 3A4 enzymes, leading to interactions with various medications. Cimetidine increases albendazole sulfoxide levels by approximately 50%. Dexamethasone increases albendazole sulfoxide levels by approximately 56%. Praziquantel increases albendazole sulfoxide levels by approximately 50%. Anticonvulsants (carbamazepine, phenytoin, phenobarbital) decrease albendazole sulfoxide levels by approximately 50%. Theophylline levels may be increased requiring monitoring. Warfarin effects may be potentiated requiring INR monitoring. Oral contraceptives may have reduced efficacy requiring additional contraceptive methods. Grapefruit juice may increase bioavailability through CYP3A4 inhibition.
Missed dose
If a dose is missed, it should be taken as soon as remembered unless it is nearly time for the next scheduled dose. In that case, the missed dose should be skipped and the regular dosing schedule resumed. Doubling of doses is not recommended. For single-dose regimens for intestinal parasites, the dose may be taken when remembered regardless of timing. For multi-day regimens, maintaining consistent dosing intervals is important for therapeutic efficacy. Patients should be advised to maintain a dosing diary or use reminder systems to ensure adherence to the treatment regimen, particularly for conditions requiring extended therapy.
Overdose
Symptoms of overdose may include severe nausea, vomiting, abdominal cramping, diarrhea, dizziness, and headache. In massive overdoses, central nervous system depression, hepatic injury, or bone marrow suppression may occur. There is no specific antidote for albendazole overdose. Management should include gastric lavage if presentation is within one hour of ingestion, activated charcoal administration, and supportive care. Liver function tests and complete blood counts should be monitored for several weeks following significant overdose. Hemodialysis is not effective due to high protein binding. Symptomatic treatment should be provided for gastrointestinal distress. Medical toxicology consultation is recommended for significant overdoses.
Storage
Store at controlled room temperature between 15-30°C (59-86°F). Protect from light and moisture. Keep container tightly closed. Do not remove desiccant from packaging. Keep out of reach of children and pets. Do not use if tablets show signs of discoloration, cracking, or deterioration. Do not transfer to other containers unless specifically designed for medication storage. Check expiration date before administration. Properly dispose of expired or unused medication through medication take-back programs or according to local regulations. Do not flush down toilets or pour into drains.
Disclaimer
This information is provided for educational purposes only and does not constitute medical advice. Individual patient requirements may vary based on specific clinical circumstances. Healthcare providers should exercise professional judgment in determining appropriate therapy. The prescribing physician should be consulted for specific dosing recommendations and treatment duration. This monograph does not cover all possible uses, directions, precautions, or adverse effects. Patients should be instructed to read the patient information leaflet provided with their medication. In case of emergency or adverse reaction, seek immediate medical attention.
Reviews
Clinical studies demonstrate cure rates of 72-98% for ascariasis, 92-100% for hookworm, and 28-88% for trichuriasis with single-dose therapy. For neurocysticercosis, albendazole shows 80-85% reduction in number of viable cysts and 60-70% complete resolution rates. In hydatid disease, studies indicate 30-50% cure rates and 50-70% improvement rates with cyclic therapy. Systematic reviews confirm albendazole’s superiority over mebendazole for soil-transmitted helminths. The medication is included on the WHO Model List of Essential Medicines and has been used in over 500 million treatments worldwide with an established safety profile. Long-term follow-up studies show sustained efficacy with minimal development of resistance despite widespread use.