Albendazole


Albendazole is a broad-spectrum antihelmintic and antiprotozoal agent of the benzimidazole type. It is used for the treatment of a variety of intestinal parasite infections, including ascariasis, pinworm infection, hookworm infection, trichuriasis, strongyloidiasis, taeniasis, clonorchiasis, opisthorchiasis, cutaneous larva migrans, giardiasis, and gnathostomiasis, among other diseases.
Common side effects include nausea, abdominal pain, and headache. Rare but potentially serious side effects include bone marrow suppression which usually improves on discontinuing the medication. Liver inflammation has been reported and those with prior liver problems are at greater risk. It is pregnancy category D in Australia, meaning it may cause harm if taken by pregnant women.
Albendazole was developed in 1975. It is on the World Health Organization's List of Essential Medicines. Albendazole is available in a fixed-dose combination with ivermectin.

Medical uses

Albendazole is an effective treatment for:
  • Flatworms
  • * Clonorchiasis
  • * Fasciolosis
  • * Opisthorchiasis
  • * Cestodes, as an alternative to praziquantel or niclosamide for adult beef tapeworms and as an alternative to praziquantel for pork tapeworms. It is also given for infections by T. crassiceps. Though praziquantel is often better at treating tapeworm infections, albendazole is used more often in endemic countries due to being cheaper and having a broader spectrum.
  • ** Cysticercosis, which is caused by the larval form of the pork tapeworm. Old cysts are not affected.
  • ** Echinococcosis of the liver, lung, and peritoneum when surgical excision is not possible. Alveolar and cystic echinococcosis may require lifelong treatment with albendazole, which only prevents the parasites from growing and reproducing rather than killing them.
  • Nematodes
  • * Anatrichosomiasis
  • * Angiostrongyliasis
  • * Anisakiasis
  • * Ascariasis, which can be cured with a single dose of albendazole.
  • * Baylisascariasis, caused by the raccoon roundworm. Albendazole can achieve good results if treatment is initiated within 72 hours of ingestion of the egg-containing raccoon feces. Corticosteroids are sometimes added in cases of eye and CNS infections.
  • * Pinworm infection
  • * Filariasis; since albendazole's disintegration of the microfilariae can cause an allergic reaction, antihistamines or corticosteroids are sometimes added to treatment. In cases of lymphatic filariasis caused by Wuchereria bancrofti or Brugia malayi, albendazole is sometimes given as an adjunct to ivermectin or diethylcarbamazine in order to suppress microfilaremia. It can also be given for Loa loa filariasis as an adjunct or replacement to diethylcarbamazine. Albendazole has an embryotoxic effect on Loa loa adults and thus slowly reduces microfilaremia.
  • * Gnathostomiasis when caused by Gnathostoma spinigerum. Albendazole has a similar effectiveness to ivermectin in these cases, though it needs to be given for 21 days rather than the 2 days needed for ivermectin.
  • * Gongylonemiasis
  • * Hepatic capillariasis caused by Capillaria hepatica
  • * Hookworm infections, including cutaneous larva migrans caused by hookworms of genus Ancylostoma. A single dose of albendazole is sufficient to treat intestinal infestations by A. duodenale or Necator americanus.
  • * Intestinal capillariasis, as an alternative to mebendazole
  • * Mansonelliasis when caused by Mansonella perstans. Albendazole is effective against adult worms but not against the immature microfilariae.
  • * Oesophagostomumiasis, when caused by Oesophagostomum bifurcum
  • * Strongyloidiasis, as an alternative to ivermectin or thiabendazole. Albendazole can be given with diethylcarbamazine to lower microfilaremia levels.
  • * Toxocariasis, also called "visceral larva migrans", when caused by the dog roundworm Toxocara canis or cat roundworm T. catis. Corticosteroids can be added in severe cases, and surgery might be required to repair secondary damage.
  • * Trichinosis, when caused by Trichinella spiralis or T. pseudospiralis. Albendazole has a similar efficacy to thiabendazole, but fewer side effects. It works best when given early, acting on the adult worms in the intestine before they generate larva that can penetrate the muscle and cause a more widespread infection. Corticosteroids are sometimes added on to prevent inflammation caused by dying larva.
  • * Trichostrongyliasis, as an alternative to pyrantel pamoate. A single dose is sufficient for treatment.
  • * Trichuriasis, sometimes considered as an alternative to mebendazole and sometimes considered to be the drug of choice. Only a single dose of albendazole is needed. It can also be given with ivermectin.
  • Giardiasis, as an alternative or adjunct to metronidazole, especially in children
  • Microsporidiosis, including ocular microsporidiosis caused by Encephalitozoon hellem or E. cuniculi, when combined with topical fumagillin
  • Granulomatous amoebic encephalitis, when caused by the amoeba Balamuthia mandrillaris, in combination with miltefosine and fluconazole
  • Arthropods
  • * Crusted scabies, when combined with topical crotamiton and salicylic acid
  • * Head lice infestation, though ivermectin is much better
  • * Intestinal myiasis
Though albendazole is effective in treating many diseases, it is only FDA-approved for treating hydatid disease caused by dog tapeworm larvae and neurocysticercosis caused by pork tapeworm larvae.

Ivermectin/albendazole

When co-administered, ivermectin and albendazole act in synergy. Ivermectin targets the parasite's nervous and muscular systems, causing paralysis, while albendazole disrupts the parasite's metabolism and microtubules by targeting tubulin polymerization. This dual approach immobilizes and kills the parasite and improves the treatment's effectiveness.
In January 2025, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive scientific opinion for ivermectin/albendazole for the treatment of infections caused by several types of worm parasites including lymphatic filariasis, a neglected tropical disease. Ivermectin/albendazole is indicated for use in people aged five years of age or older, for the treatment of soil-transmitted helminth infections, caused by different types of intestinal parasitic worms, which are spread through soil contaminated by human feces in areas with poor sanitation. Among the worms responsible for these diseases are hookworms, roundworms, whipworms and a roundworm called Strongyloides stercoralis. Ivermectin/albendazole is also indicated for the treatment of microfilaraemia in people with lymphatic filariasis. Lymphatic filariasis is a neglected tropical disease commonly known as elephantiasis, which impairs the lymphatic system and can lead to the abnormal enlargement of body parts, causing pain, severe disability and social stigma. Ivermectin/albendazole is indicated for the treatment of cases of lymphatic filariasis caused by Wuchereria bancrofti, a parasite which is responsible for 90% of cases worldwide.

Contraindications

to the benzimidazole class of compounds contraindicates its use.

Side effects

The most common side effects of albendazole are experienced by over 10% of people and include headache and abnormal liver function. Elevation of liver enzymes occurs in 16% of patients receiving treatment specifically for hydatid disease and goes away when treatment ends. Liver enzymes usually increase to two to four times the normal levels. An estimated 1–10% of people experience abdominal pain, nausea or vomiting, dizziness or vertigo, increased intracranial pressure, meningeal signs, temporary hair loss, and fever. The headache, nausea, and vomiting are thought to be caused by the sudden destruction of cysticerci, which causes acute inflammation. Fewer than 1% of people get hypersensitivity reactions such as rashes and hives, leukopenias such as agranulocytosis and granulocytopenia, thrombocytopenia, pancytopenia, hepatitis, acute liver failure, acute kidney injury, irreversible bone marrow suppression, and aplastic anemia.
Side effects can be different when treating for hydatid disease versus neurocysticercosis: for example, those being treated for the former are more likely to experience elevated liver enzymes and abdominal pain, while those being treated for the latter are more likely to experience headache. Treating hydatid disease can also unmask undiagnosed neurocysticercosis. People receiving albendazole for the treatment of neurocysticercosis can have neurological side effects such as seizures, increased intracranial pressure, and focal signs caused by the inflammatory reaction that occurs when parasites in the brain are killed. Steroids and anticonvulsants are often given with albendazole when treating neurocysticercosis to avoid these effects. Those being treated for retinal neurocysticercosis can face retinal damage if they are not first checked for ocular cysticeri, since changes to existing lesions in the eye by albendazole can cause permanent blindness.

Pregnancy

Albendazole is a pregnancy class D drug in Australia. It is contraindicated in the first trimester of pregnancy, and should be avoided up to one month before conception. While studies in pregnant rats and rabbits have shown albendazole to be teratogenic, albendazole has been found to be safe in humans during the second and third trimesters. It can, however, possibly cause infantile eczema when given during pregnancy.
In pregnant dogs, albendazole use has led to puppies with reduced weight and with cleft palates. Birds have lower rates of laying eggs and hatching when given albendazole.
The sulfoxide metabolite is secreted into breast milk at around 1.5% of the maternal dose, though oral absorption is poor enough that it is unlikely to affect nursing infants.