Albendazole

BRAND NAMES

• Albenza: The brand-name version of albendazole available in the United States.

• Zentel: A well-known global brand of albendazole, produced by GSK Pharmaceuticals.

• Eskazole: An alternative international brand name for albendazole.

MECHANISM OF ACTION

Albendazole acts by causing degenerative changes in the worm's outer surface (tegument) and intestinal cells, which reduces its ability to produce energy. This results in the parasite becoming immobilized and eventually dying. The drug works by binding to the colchicine-sensitive site on tubulin, blocking its polymerization into microtubules. Since microtubules are essential for glucose uptake in both larval and adult stages of susceptible parasites, this disruption leads to the depletion of their glycogen reserves.

PHARMACOKINETICS:

Absorption

Albendazole is poorly and inconsistently absorbed from the gastrointestinal tract because of its low water solubility. Its main therapeutic effects are primarily attributed to its active metabolite, albendazole sulfoxide, which is quickly produced following absorption.

Distribution

After being converted by the liver into its active form, albendazole sulfoxide, albendazole is rapidly and widely distributed throughout the body. Although it is poorly absorbed in the gastrointestinal tract, this can be improved by administering it with a fatty meal.

Metabolism

Albendazole is quickly metabolized in the liver into its primary active form, albendazole sulfoxide, which is subsequently broken down further into albendazole sulfone and other metabolites.

Excretion

Albendazole is mainly excreted through bile and feces, while less than 1% of the active metabolite, albendazole sulfoxide, is eliminated in the urine.

PHARMACODYNAMICS

Albendazole is a broad-spectrum anthelmintic that works by disrupting the cellular structure and function of parasitic worms. It binds selectively to β-tubulin in parasite cells, inhibiting the polymerization of tubulin into microtubules. This disruption impairs essential cellular processes, particularly glucose uptake, leading to energy depletion and eventual death of the parasite. The drug affects both larval and adult stages of susceptible helminths. Its pharmacological activity is primarily due to its active metabolite, albendazole sulfoxide.

ADMINISTRATION

For safe and effective use of albendazole, it should be taken with food—preferably a fatty meal—to enhance its absorption. The medication comes in tablet form and can be swallowed whole, chewed, or crushed and taken with water. The exact dose and length of treatment depend on the specific parasitic infection and should follow your doctor’s recommendations.

DOSAGE AND STRENGTH

Albendazole is available in 200 mg and 400 mg oral tablets and as a 200 mg/10 mL or 400 mg/20 mL oral suspension. The specific dosage and duration of treatment vary greatly depending on the type of parasitic infection, the patient's weight, and their age. 

DRUG INTERACTIONS

Albendazole, used to treat parasitic worm infections, may interact with other medications by affecting the levels of its active metabolite, albendazole sulfoxide. Such interactions can either enhance the risk of side effects or decrease the drug’s overall effectiveness.

FOOD INTERACTIONS

The most notable food interaction with albendazole occurs with fatty meals, which greatly enhance the drug’s absorption. Consuming albendazole alongside a high-fat meal can increase the absorption of its active metabolite, albendazole sulfoxide, by up to fivefold. Additionally, other substances such as grapefruit juice and alcohol may also interact with albendazole.

CONTRAINDICATIONS

The key contraindications for albendazole are pregnancy and a known hypersensitivity to the drug or other benzimidazoles. Additional important contraindications and precautions involve patients with pre-existing liver disease, neurocysticercosis, and certain age groups.

SIDE EFFECTS

Common side effects of albendazole include gastrointestinal symptoms such as nausea, vomiting, abdominal pain, and diarrhea. Headache and dizziness are also frequently reported. Liver function tests may reveal temporary elevations in liver enzymes, so your doctor might monitor your liver health with blood tests during treatment. Some patients may experience temporary hair thinning or hair loss (alopecia), which typically reverses after the treatment ends. Fever can also occur as a side effect.

OVER DOSE

An albendazole overdose can result in serious side effects, such as liver damage, blood disorders, and neurological issues. One case study documented an overdose of 300 times the recommended dose, leading to severe hair loss and other toxic effects. If an overdose is suspected, it’s crucial to seek emergency medical attention right away.

TOXICITY

Albendazole is generally well-tolerated, but its toxicity can manifest in various ways, ranging from common side effects to rare but severe reactions involving the liver, bone marrow, and central nervous system. Toxicity is more likely with high doses, prolonged use, or pre-existing conditions affecting the liver or bone marrow.