THIABENDAZOLE
Chemistry - The prototypic benzimidazole, thiabendazole occurs as an odorless or nearly odorless, tasteless, white to practically white powder. It has a melting range of 296°-303°C and a pKa of 4.7.
Thiabendazole is practically insoluble in water and slightly soluble in alcohol.
Thiabendazole is indicated (labeled) for the removal of the following parasites in cattle:
Haemonchus spp., Ostertagia spp., Trichostrongylus spp., Nematodirus spp., Cooperia spp. and Oesophagostomum radiatum.
Thiabendazole is indicated (labeled) for the removal of the following parasites in sheep and goats:
Haemonchus spp., Ostertagia spp., Trichostrongylus spp., Nematodirus spp., Cooperia spp.,
Chabertia spp., Bunostomum spp. and Oesophagostomum spp..
Thiabendazole is indicated (labeled) for the removal of the following parasites in horses:
Strongylus spp., craterstomum spp., Oesphagodontus spp., Posteriostomum spp., Cyathostomumspp., Cylicocylus spp., Cylicostephanus spp., Oxyuris spp., and Parasacaris spp..
Thiabendazole is indicated (labeled) for the removal or prevention of the following parasites inswine: large roundworms (Ascaris suum) (prevention), and in baby pigs infested with
Strongyloides ransomi.
Although not approved, thiabendazole has been used in pet birds and llamas. See the Dosagesection for more information.
In many geographic areas, significant thiabendazole resistance problems have developed and formany parasites other anthelmintics would be a better choice for treatment.
Absorbed drug is rapidly metabolized in the liver by hydroxylation, glucuronidation and sulfateformation. Within 48 hours of dosing, 90% of the drug is excreted in the urine (as metabolites) and5% in the feces. Less than 1% of the drug is excreted in the urine unchanged. Five days after adose, the drug is virtually eliminated from the body.
Contraindications/Precautions - Thiabendazole has not been demonstrated to be a teratogen andis considered to be generally safe to use during pregnancy. However, in high doses it has beenimplicated in causing toxemia in ewes.
Overdosage/Toxicity - Thiabendazole has a safety margin of at least 20 times the recommendeddose in horses. Doses of 800 - 1000 mg/kg are necessary to cause anorexia and depression insheep. The minimum lethal dose is 700 mg/kg in cattle and 1200 mg/kg in sheep.
It is unlikely that a modest overdose would cause significant problems. If a massive overdoseoccurs, treat supportively and symptomatically. See the Adverse effects section for more information.
Thiabendazole is practically insoluble in water and slightly soluble in alcohol.
Storage, Stability, Compatibility
Thiabendazole tablets, boluses and oral suspension should bestored in tight containers.Uses, Indications
Thiabendazole has been used for the removal of the following parasites indogs: ascarids (Toxocara canis, T. leonina), Strongyloides stercoralis, and Filaroides. It has alsobeen used systemically as an anti-fungal agent in the treatment of nasal aspergillosis and penicillinosis. Topical and otic use of thiabendazole for the treatment of various fungi is also commonlyemployed.Thiabendazole is indicated (labeled) for the removal of the following parasites in cattle:
Haemonchus spp., Ostertagia spp., Trichostrongylus spp., Nematodirus spp., Cooperia spp. and Oesophagostomum radiatum.
Thiabendazole is indicated (labeled) for the removal of the following parasites in sheep and goats:
Haemonchus spp., Ostertagia spp., Trichostrongylus spp., Nematodirus spp., Cooperia spp.,
Chabertia spp., Bunostomum spp. and Oesophagostomum spp..
Thiabendazole is indicated (labeled) for the removal of the following parasites in horses:
Strongylus spp., craterstomum spp., Oesphagodontus spp., Posteriostomum spp., Cyathostomumspp., Cylicocylus spp., Cylicostephanus spp., Oxyuris spp., and Parasacaris spp..
Thiabendazole is indicated (labeled) for the removal or prevention of the following parasites inswine: large roundworms (Ascaris suum) (prevention), and in baby pigs infested with
Strongyloides ransomi.
Although not approved, thiabendazole has been used in pet birds and llamas. See the Dosagesection for more information.
In many geographic areas, significant thiabendazole resistance problems have developed and formany parasites other anthelmintics would be a better choice for treatment.
Pharmacokinetics - THIABENDAZOLE
Thiabendazole is relatively well absorbed (for a benzimidazole) and is distributed throughout body tissues. Peak levels occur in approximately 2-7 hours after dosing.Absorbed drug is rapidly metabolized in the liver by hydroxylation, glucuronidation and sulfateformation. Within 48 hours of dosing, 90% of the drug is excreted in the urine (as metabolites) and5% in the feces. Less than 1% of the drug is excreted in the urine unchanged. Five days after adose, the drug is virtually eliminated from the body.
Contraindications/Precautions - Thiabendazole has not been demonstrated to be a teratogen andis considered to be generally safe to use during pregnancy. However, in high doses it has beenimplicated in causing toxemia in ewes.
Adverse Effects, Warnings
At recommended doses, thiabendazole is usually well tolerated byapproved species. In dogs, vomiting, diarrhea, hair loss and lethargy are possible side effects, no-tably with high dose or long-term therapy. Dachshunds have been reported to be particularly sensitive to thiabendazole. Toxic epidermal necrolysis (TEN) has been reported in dogs receivingthiabendazole, but the incidence appears to be very rare.Overdosage/Toxicity - Thiabendazole has a safety margin of at least 20 times the recommendeddose in horses. Doses of 800 - 1000 mg/kg are necessary to cause anorexia and depression insheep. The minimum lethal dose is 700 mg/kg in cattle and 1200 mg/kg in sheep.
It is unlikely that a modest overdose would cause significant problems. If a massive overdoseoccurs, treat supportively and symptomatically. See the Adverse effects section for more information.