Pharmacokinetics and distribution of Huwen toxin—1 after epidural and intravenous administration to rhesus monkeys

Huwen toxin-1(HWTX-1) was adminstered at a dose of 0.388 MBq·kg^-1 by lumbar puncture at the third and the fourth lumbar interspace or ivat the same dose.Comcentrations were determined by reverse phase-high performance liquid chromatography.Tissue distribution was detected by γ-counter.Radioactivity detected in epidural space was 38% of injected radioactivity at 10min after injection.The maximum plasma concentration after epidural or iv administration were(0.70±0.04) and (5.0±0.6)MBq·L^-1,respectively.The maximum plasma concentration intimes were 30 and 2 min,respectively.Teminal T1/2 were(10.36±0.27) and (11.03±1.16)h,respectively.Cls were(1.29±0.07) and (1.25±0.23)L·h^-1·kg^-1,respectively,Bioavailabilit after epidural administration was>90%.Distributions of [^125I] HWTX-1 between two routes were different,and the exposed levels in most tissues at 10min after iv were higher than those after epidural administration(P>0.05).