Altered plasma and brain disposition of isopropylidene shikimic acid liposome in rats and the brain protection in cerebral ischemia-reperfusion

Context: Cerebral ischemia-reperfusion (I/R) injury is a secondary injury caused by oxidative stresses and inflammatory responses after recovery from cerebral ischemia. Brain protective drugs were used to reduce the injury. In order to improve the distribution in brain and enhance the brain-protective efficacy, some pharmaceutical technologies were used to achieve brain targeting delivery. Objective: To investigate the physiological disposition of ISA liposome, and provide references for the further study about high-efficacy brain-protective preparations for I/R injury. Materials and methods: Comparative studies were carried out. The pharmacodynamics in t-MCAO model rats were studied first, and then the pharmacokinetics and brain distribution of the two preparations were determined. Results: At the same dose, the efficacy of ISA liposome was better (P < 0.05). The efficacy was dose dependent, with significant difference of 20 mg/kg (P < 0.01) and indistinctive difference of 10 mg/kg (P = 0.22), compared with vehicle-treated rats. The parameters, T-1/2 beta, MRT and AUC were different significantly between the two preparations. The enhancement of brain distribution for ISA in the liposome was obvious, with the maximum concentration 7.18 mu g/g, while close to zero for the solution group. Discussion and conclusion: ISA liposome could increase the distribution in brain and enhance the efficacy significantly. The results revealed that the liposomal DDS was potential as a novel strategy for the treatment of cerebral I/R injury. In addition, further targeted modification, such as PEG-modified liposomes, which possess a long circulating property in the bloodstream, would further improve the targeting delivery to the brain and lead to more significant efficacy.