Objective: The aim of this study was to investigate the steady-state brain-plasma concentration ratio of morroniside in focal cerebral ischemia-reperfusion model rats. Method: The in vivo rat model was established. The middle cerebral artery occlusion was induced by the intraluminal filament technique. The concentrations of morroniside in the plasma and brain of rats were determined from normal control group

sham-operated group and focal cerebral ischemia- reperfusion model group

and the blood brain partitioning(lg BB) of morroniside was calculated while the plasma concentration of morroniside was in the steady-state via intravenous drip (55 min) by LC-MS/MS. Result: Morroniside almost could not pass through the blood brain barrier in normal rats. The lg BB of morroniside in the left and right brain of focal cerebral ischemia-reperfusion model rats were (1.36±0.44) and (2.26±0.13)

respectively

which were significantly higher than the normal control group and sham-operated group rats. Conclusion: The results demonstrated that morroniside could pass through the blood brain barrier in rats in focal cerebral ischemia-reperfusion model group more easily than normal control and sham-operated group.