The Efficacy of Thiabendazole against Hookworm and Ascaris of Man

Abstract

Thiabendazole, in the dosage of 2 g, approximately 40 mg/kg, as a single dose for 1 day in adult patients, has a moderate anthelmintic activity against both A. duodenale and N. americanus as judged by egg-count reduction. Twenty-five mg/kg on 2 consecutive days was less effective. However, the real efficacy of this drug against hookworm is not so great as the degree of egg reduction suggests, for subsequent therapy with bephenium hydroxynaphthoate removed a large number of worms. This compound also has anthelmintic efficacy for A. lumbricoides infection in man, a dose of 25 mg/kg on 2 successive days reduced the egg count 75%. No activity against T. trichiura was found. Although transient side reactions of dizziness and nausea following administration of the drug are not serious, the incidence of these reactions is high. A new compound, thiabendazole, synthesized by Merck Sharp and Dohme (Brown et al., 1961) has been found to be a promising broad-spectrum anthelmintic against numerous gastrointestinal nematodes in domestic animals (Campbell and Cuckler, 1962; Drudge and Szanto, 1962; Drudge et al., 1962; Egerton et al., 1962; Herlich, 1962). Franz (1963) found it effective in human strongyloidiasis. Extensive unpublished studies by groups cooperating with the Merck Institute for Therapeutic Research indicate that thiabendazole has a broad spectrum against helminths of man. However, since there are considerable unexplained variations in the reported activity of this compound against hookworm, ascaris, and Trichuris, the present study was designed to evaluate the efficacy of this drug against human hookworm and ascaris infections. The Merck Institute for Therapeutic Research has made extensive acute and chronic toxicity studies on thiabendazole in animals. It is well tolerated by man and careful hematological and biochemical studies designed to measure hemapoietic, liver, and kidney functions of patients receiving this drug revealed no abnormalities. The compound is colorless, stable, and tasteless, and may therefore be Received for publication 24 May 1963. useful in the treatment of helminthic infection