title: Uptake and effect of praziquantel and the major human oxidative metabolite, 4-hydroxypraziquantel, by Schistosoma japonicum.
abstract: After exposure to praziquantel in vitro at a concentration of 1 microgram/ml for 0.5-2 hr, amounts of praziquantel in Schistosoma japonicum varied from 2.1 +/- 1.2 to 3.7 +/- 1.6 ng/male worm and 1.3 +/- 1.2 to 2.2 +/- 1.5 ng/female worm during the time studied. At 30 micrograms/ml, praziquantel amounts were 11-33-fold higher. However, within 2 hr after removal from a medium containing 30 micrograms/ml praziquantel, 95% of the drug was released from the parasites. When S. japonicum worm pairs were incubated in vitro with 1, 10, and 30 micrograms/ml of 4-hydroxypraziquantel, the major human oxidative metabolite of praziquantel, 0.2 +/- 0.2, 3.8 +/- 1.3, and 7.4 +/- 1.3 ng/worm pair, respectively, were found after a 2-hr incubation. 15-30-fold lower than corresponding worm pair amounts of praziquantel. In vivo, when 4- or 5-wk S. japonicum-infected mice were treated orally with praziquantel (300 mg/kg), peak concentrations of praziquantel in plasma determined by high pressure liquid chromatography were 14.7 +/- 1.5 micrograms/ml (4-wk infection) and 16.7 +/- 2.8 micrograms/ml (5-wk infection) 15 min after treatment. Corresponding in vivo worm praziquantel amounts were 1.8 +/- 0.4 ng/male worm and 2.4 +/- 1.1 ng/female worm, respectively, in the 4-wk infection and 4.6 +/- 1.6 ng/male worm and 5.6 +/- 1.2 ng/female worm in the 5-wk infection. Peak plasma concentrations of 4-hydroxypraziquantel were similar but corresponding in vivo worm amounts were 1-20-fold lower, depending on the time after drug administration.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Institute of Parasitic Diseases, Chinese Academy of Preventive Medicine, Shanghai, China.
authors.forename: S H
authors.initials: SH
authors.lastname: Xiao
authors.forename: J Q
authors.initials: JQ
authors.lastname: You
authors.forename: H F
authors.initials: HF
authors.lastname: Guo
authors.forename: B A
authors.initials: BA
authors.lastname: Catto
mesh_terms: D000818:Animals; D005260:Female; D008297:Male; D051379:Mice; D011223:Praziquantel / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use; D012549:Schistosoma japonicum / Q000187:drug effects / Q000378:metabolism*; D012554:Schistosomiasis japonica / Q000188:drug therapy* / Q000378:metabolism
chemical_list: C067550:4-hydroxypraziquantel; D011223:Praziquantel