The tegumental changes in adult Opisthorchis viverrini induced by tribendimidine were analyzed by scanning electron microscopy (SEM). We exposed O. viverrini to tribendimidine at a concentration of 10μg/ml for 4h. In addition, hamsters were treated with a single 400mg/kg oral dose of tribendimidine and flukes were recovered from the bile ducts 24, 48, 72, and 96h post-treatment. SEM analysis of the flukes incubated in vitro showed only mild damage of the tegument. Twenty-four hours post-treatment of hamsters, extensive disruption such as sloughing, furrowing, or blebbing of the tegument was evident, which did not increase in severity 48-72h post-treatment. Ninety-six hours after tribendimidine administration, the majority of flukes had been expelled. A single 400mg/kg oral dose of tribendimidine administered to O. viverrini-infected hamsters yielded a worm burden reduction of 63.0%. In conclusion, our experiments confirm that tribendimidine possesses interesting trematocidal properties, which warrant additional investigations and provide further data for subsequent clinical trial
