In vitro and in vivo effect of levopraziquantel, dextropraziquantel versus racemic praziquantel on different developmental stages of Schistosoma japonicum.
OBJECTIVE
To compare the antischistosomal effect of racemic praziquantel (Pra) and its enantiomers, levopraziquantel (L-Pra) and dextropraziquantel (D-Pra), on different developmental stages of Schistosoma japonicum.


METHODS
The in vitro effects of the drugs were determined in different stages of schistosomes maintained in RPMI 1640 supplemented with 20% calf serum. In vivo study mice infected with schistosome cercariae were treated intragastrically (ig) with Pra, L-Pra or D-Pra at different intervals after infection. The efficacy of the drugs was evaluated by residual mean worm number.


RESULTS
Based on the degree of tegument damage induced by L-Pra, d28 and d35 schistosomes were most susceptible to L-Pra, while d14 schistosomules being least susceptible. At comparable concentrations of 0.1-1 g/ml, L-Pra was more active than Pra even when the concentration of L-Pra was reduced to one-half of the minimum effective concentration of Pra. At above-mentioned concentrations D-Pra exhibited no apparent in vitro effect on different stages of schistosomes. When infected mice were treated ig with L-Pra, Pra or D-Pra at a single dose of 300 mg/kg or 500 mg/kg, only the former two drugs showed apparent effect on d0, d21, d28 and d35 schistosomes and less or much less effect on d3, d7 and d14 schistosomules. D-Pra only exhibited a negligible effect on d35 adult schistosomes as compared with L-Pra and Pra. When mice infected with d35 adult schistosmes were treated ig with L-Pra 150 mg/kg, the efficacy was similar to that of mice treated with Pra 300 mg/kg.


CONCLUSIONS
L-Pra is the principal active component against schistosomes in racemic Pra.
Xiao
S
S
Institute of Parasitic Diseases, Chinese Academy of Preventive Medicine, WHO Collaborating Center for Malaria, Schistosomiasis and Filariasis, Shanghai 200025, China.
You
J
J
Mei
J
J
Hu
Y
Y
Zhou
D
D
Catto
B A
BA
D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D051379:Mice; D011223:Praziquantel / Q000494:pharmacology*; D012549:Schistosoma japonicum / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D012554:Schistosomiasis japonica / Q000188:drug therapy / Q000469:parasitology; D013237:Stereoisomerism
D000871:Anthelmintics; D011223:Praziquantel