Opisthorchis viverrini: efficacy and tegumental alterations following administration of tribendimidine in vivo and in vitro.

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 10 microg/ml for 4 h. In addition, hamsters were treated with a single 400 mg/kg oral dose of tribendimidine and flukes were recovered from the bile ducts 24, 48, 72, and 96 h 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 48-72 h post-treatment. Ninety-six hours after tribendimidine administration, the majority of flukes had been expelled. A single 400 mg/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 trials.