EXPERIMENTAL CHEMOTHERAPY OF CLONORCHIS SINENSIS AT DIFFERENT DEVELOPING STAGE IN RATS WITH PRAZIQUANTEL

To further investigate the efficacy and mechanism of action of Praziquantel against Clonorchis sinensis, the effect of different doses of the drug (single dose) on worms of different developing stages in rats and the dynamic morphological changes of the worms at various times after administration were observed.1. All the rats treated with 300 mg/kg or 400 mg/kg on the 5 th hour or 13 th day of infection and those with 400 mg/kg on the 5 th day achieved complete cure. A dose of 300 mg/kg given on the 5 th day also showed remarkable effect. The results suggest that the worms were killed by Praziquantel at the immature stage, thus preventing the hazard from mature worms.2. Treatment on the 68～74 th day of infection gave the following results: 500 mg/kg: complete cureof all rats; 400 mg/kg or 300 mg/kg: low rate of worm recovery; 200 mg/kg: poor effect.The number and rate of worm recovery of control group were 18.8±4.4 and 62.7%±14.7%, respectively.3. Thirty six hours or 48 hours after administration of Praziquantel at a single dose of 300 mg/kg or 400 mg/kg the number of the worms recovered decreased significantly.The worms became thiner, greyish in colour and deformed. Microscopic observation showed that the cuticle peeled in some part of the body wall, the structures of testes became looser with many blank areas. Transmission electromicroseopy showed that the tegument epithelial cells and muscles were lysed and lost their normal structures.These results demonstrate that Praziquantel is a quick and highly effective, ideal drug for Clonorchiasis.