EFFECT OF PYQUITON DERIVATIVES IN EXPERIMENTAL SCHISTOSOMIASIS JAPONICA

Four pyquiton (praziquantel) derivatives coded as S77078, S78015, S79046 and 21542 have been found to possess ,cidal action on schistosome in screening test.Mice, rabbits and dogs were each exposed to 48～52 and 248～252 Schistosoma japonicum cercariae. When infected mice were treated orally with S78015, S 79046 and 21542 suspension at dosages, of 200～400 mg/kg/day for 2 days, the worm reduction rates were 22.5～53.9%, 27.6% and 32.8～66.9%, respectively; while the animals treated with 77078 at dosages of 200～600 mg/kg/day for 1～2 days. resulted in worm reduction rates of 60.1～97.3%, which were comparable to those of pyquiton 83.6～95.6%. In infected rabbits treated orally with S 77078 suspension or intramuscularly with the drug in PEG solution at dosages of 30～60 mg/kg/ day for 1～2 days, and in infected dogs treated orally with the drug suspension at dosages of 10～20 mg/kg tid for 1～2 days, the worm reduction rates were 18.3～40.8,% and 53.7～80.4%, respectively, which were lower than the 97.1～97.3% and 89.7～98.5% for pyquiton.The oral LD₅₀ of S 77078 and pyquiton in normal mice were 1,530 mg/kg and 2,280 mg/kg, respectively; while ED₅₀ in infected mice were 215 mg/kg and 230 mg/kg respectively.