Effect of artemether against Schistosoma japonicum

Artemether (beta-methyl ether of artemisinin) first synthesized by Shanghai Institute of Materia Medica, Chinese Academy of Sciences(1), appears in colorless crystal and is more lipid-soluble than artemisinin. When artemether was given ig or im to mice infected with Schistosoma japonicum for 32-35 d at the dosage of 1/10-1/2 LD50. Its effects in the two administration routes were similar. After artemether 200 mg.kg.d-1 ig or 100 mg.kg-1.d-1 im for 1-2 d was given to mice infected with S japonicum cercariae at different intervals, d 7 schistosomules were more susceptible to the drug with worm reduction rates of 73.9-92.0%. The d 35 adult worms also exhibited susceptibility to the drug and the worm reduction rates were 47.0-70.1%, but less susceptibility to the drug in other developmental stages of schistosomes. The major morphological alteration of adult worms induced by artemether was sustained shrinkage accompanied by atrophy and degeneration of the worm's reproductive glands, eg, the testis in males and ovary as well as vitelline gland in females. The in vitro tests indicated that artemether showed apparent effects on different stages of schistosomes only when a higher concentration of 40 micrograms.ml-1 was used.