Albendazole as a fasciolicide in experimentally infected sheep.

The new drug albendazole (methyl [5-(propylthio)-1H-benzimidazol-2-yl]carbamate) was tested in 90 sheep experimentally infected with Fasciola hepatica. Dose rates of 10, 15, and 20 mg/kg of body weight were active against adult flukes, with efficacies of 98, 95, and 100% respectively. The drug was less active against immature F hepatica at 3 weeks after sheep were inoculated. The drug given at dose rates of 20, 30, 40, and 50 mg/kg had efficacies 24, 47, 63, and 76%. Flukes were not found at posttreatment hour 48 in bile ducts of sheep given a dose of 20 mg/kg. Evidence of drug toxicity was not seen.