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The relationship between plasma level and therapeutic efficacy of praziquantel (PZQ) and its major human oxidative metabolite, 4-hydroxypraziquantel (4-OHPZQ), has been investigated in Schistosoma japonicum-infected rabbits using three different routes of PZQ administration. After intramuscular administration (20 mg/kg), the maximum level of PZQ in rabbit cardiac plasma was 1.6 ± 1.0 µg/ml (mean ± SD) 30 min after administration. After oral or rectal administration (40 mg/kg), maximum plasma levels were 0.1 ± 0.2 µg/ml (oral) and 0.5 ± 0.4 µg/ml (rectal). The corresponding maximum 4-OHPZQ concentrations in cardiac plasma were 4.6 ± 1.8 µg/ml (intramuscular), 1.7 ± 0.5 µg/ml (oral), and 4.1 ± 1.6 µg/ml (rectal) 2 hr after administration of PZQ. After administration of similar doses, maximum levels of PZQ in plasma from the femoral vein were 29.3 ± 27.5 µg/ml (intramuscular), 0.6 ± 1.0 µg/ml (oral), and 0.7 ± 0.6 µg/ml (rectal). However, 60 min after intramuscular administration, the maximum PZQ concentration in portal venous blood was only 1.0 ± 0.6 µg/ml, which is substantially less than corresponding maximum portal vein levels after oral (6.8 ± 6.5 µg/ml) or rectal (3.7 ± 4.6 µg/ml) administration. Therapeutically, in spite of the 4ā6-fold lower levels of PZQ in portal venous plasma after intramuscular administration, adult worm reduction rates in infected rabbits using the above doses were 92.2% (intramuscular), 90.1% (rectal), and 72.5% (oral), respectively, four weeks after treatment. Thus, no direct correlation between levels of PZQ in peripheral or portal venous blood and therapeutic efficacy was observed in rabbits infected with S. japonicum.
Past two years | Past Year | Past 30 Days | |
---|---|---|---|
Abstract Views | 215 | 96 | 4 |
Full Text Views | 9 | 0 | 0 |
PDF Downloads | 7 | 0 | 0 |