In man, thiabendazole is rapidly absorbed and peak plasma concentration is reached within 1 to 2 hours after the oral administration of a suspension. It is metabolized almost completely to the 5-hydroxy form which appears in the urine as glucuronide or sulfate conjugates. In 48 hours, about 5% of the administered dose is recovered from the feces and about 90% from the urine. Most is excreted in the first 24 hours.
Mechanism of Action
The precise mode of action of thiabendazole on the parasite is unknown, but it may inhibit the helminth-specific enzyme fumarate reductase.
Thiabendazole is vermicidal and/or vermifugal against Ascaris lumbricoides (“common roundworm”), Strongyloides stercoralis (threadworm), Necator americanus, and Ancylostoma duodenale (hookworm), Trichuris trichiura (whipworm), Ancylostoma braziliense (dog and cat hookworm), Toxocara canis and Toxocara cati (ascarids), and Enterobius vermicularis (pinworm).
Its effect on larvae of Trichinella spiralis that have migrated to muscle is questionable.
Thiabendazole also suppresses egg and/or larval production and may inhibit the subsequent development of those eggs or larvae which are passed in the feces.