Therapy of fluke infections in the past. A review

Chemotherapy of trematode infections has been studied intensively in the past. The compounds so far used for the treatment of those parasitic infections were not satisfactory, however, because of their poor tolerability and/or their limited anthelmintic efficacy. Since the introduction of tartar emetic in 1918, a number of antimonial as well as non-antimonial preparations have been used for the treatment of schistosomiasis. In the treatment of clonorchiasis with antimony preparations, gentian violet, emetine HCl, chloroquine diphosphate and dithiazanine iodide, only temporary clinical improvement and negative or reduced egg counts could be achieved, but complete cure was not obtained. Although Hetol (or hexachloroparaxylol), prolonged administration of oral dehydroemetine and only two doses of niclofolan showed therapeutic effect on Clonorchis infection, side effects were observed in most of the treated cases. On the other hand, bithionol proved to be a drug of choice for paragonimiasis. However, the need of multiple doses and the many adverse reactions hampered its use in the field. Recently the newly developed praziquantel (2-cyclohexylcarbonyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino-[2,1-a]+ ++isoquinolin -4-one, EMBAY 8440, Biltricide) proved to be safe and effective against trematodes and appears to be the drug of choice for infections due to all species of Schistosoma, Clonorchis sinensis, Opisthorchis viverrini, Paragonimus spp. and Metagonimus yokogawai in man.