Praziquantel: a new schistosomicide against Schistosoma mansoni.

2-Cyclo-hexylcarbonyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a]isoquinolin-4-one (praziquantel, EMBAY 8440, Biltricide), a new schistosomicide, given to subjects with Schistosoma mansoni infections in a single oral dose of 40 mg/kg or 50 mg/kg in 2 divided doses resulted in probable cure rates at 6 months of 74% and 88.1%, respectively. The corresponding reduction in egg excretion of the non-cured cases was 96.9% and 97.3%. Side effects were not severe but included urticaria, loose bowel motions, abdominal pain and sleepiness.