The present study was undertaken to evaluate in vitro activities of following drugs against adult worms of Clororchis sinensis: i.e., stibnal, chloroquine diphosphate, Hetol (1,4-bis-trichloromethylbenzol), dehydroemetine 'Roche' (Ro 1-9334), niridazole (Ambilhar), bisbendazole, gentian violet, dithiazanine iodide, hexachlorophene, bithionol, niclofolan (Bilevon, Bayer 9015) and praziquantel (Embay 8440, Biltricide). After isolation from bile ducts of experimentally infected rabbits (3 months infection), the parasites were rinsed in sterilized Tyrode's solution and incubated for 24 hours at 37 C in TC 199 medium with Earle's balanced salt solution containing 0, 0.01, 0.1, 1.0, 10 and 100 microgram/ml concentrations of each above drugs. The activities of each concentrations with each drugs were evaluated by the motility of the worms in culture tubes observing at 15, 30, 60 minutes and 2, 4, 6, 12, 18 and 24 hours by stereomicroscope. In the results, no effect was found at the adult worms of C. sinensis in all concentrations with stibnal, chloroquine diphosphate, Hetol, dehydroemetine, niridazole and bisbendazole. However, moderate activities were observed in the concentrations of 1.0 and 0.1 microgram/ml of gentian violet, dithiazanine iodide, hexachlorophene and bithionol. The highest activities were observed in all concentrations of niclofolan and praziquantel.
