Release rate is a key variable affecting the therapeutic effectiveness of liposomal fasudil for the treatment of cerebral ischemia/reperfusion injury.

Liposomal fasudil as a treatment for cerebral ischemia/reperfusion (I/R) injury has been demonstrated to be effective in animal models due to the high accumulation of liposomes in damaged brain tissue. However, it is still unclear what effect drug release rate has on the treatment of I/R injury, where pathology progresses dramatically in a short time. In the present study, we assessed four formulations of liposomal fasudil. The results of an in vitro drug release assay showed that the release properties of fasudil were changed by varying the lipid composition and internal phase of the liposomes. Based on these results, differences in the transition of fasudil plasma concentration were monitored after the administration of each type of liposomal fasudil in normal rats. A pharmacokinetic study showed that higher levels of drug retention in liposomal fasudil resulted in higher fasudil plasma concentration. Finally, treatment of I/R injury model rats with liposomal fasudil revealed that a mid-level release rate of fasudil from liposomes resulted in the greatest therapeutic effect among the formulations. In conclusion, these results demonstrate that an optimized drug release rate from liposomes enhances the therapeutic effect of fasudil for the treatment of cerebral I/R injury.

Combination therapy with liposomal neuroprotectants and tissue plasminogen activator for treatment of ischemic stroke.

For ischemic stroke treatment, extension of the therapeutic time window (TTW) of thrombolytic therapy with tissue plasminogen activator (tPA) and amelioration of secondary ischemia/reperfusion (I/R) injury are most desirable. Our previous studies have indicated that liposomal delivery of neuroprotectants into an ischemic region is effective for stroke treatment. In the present study, for solving the above problems in the clinical setting, the usefulness of combination therapy with tPA and liposomal fasudil (fasudil-Lip) was investigated in ischemic stroke model rats with photochemically induced thrombosis, with clots that were dissolved by tPA. Treatment with tPA 3 h after occlusion markedly increased blood-brain barrier permeability and activated matrix metalloproteinase (MMP)-2 and -9, which are involved in cerebral hemorrhage. However, an intravenous administration of fasudil-Lip before tPA markedly suppressed the increase in permeability and the MMP activation stemming from tPA. The combination treatment showed significantly larger neuroprotective effects, even in the case of delayed tPA administration compared with each treatment alone or the tPA/fasudil-treated group. These findings suggest that treatment with fasudil-Lip before tPA could decrease the risk of tPA-derived cerebral hemorrhage and extend the TTW of tPA and that the combination therapy could be a useful therapeutic option for ischemic stroke.-Fukuta, T., Asai, T., Yanagida, Y., Namba, M., Koide, H., Shimizu, K., Oku, N. Combination therapy with liposomal neuroprotectants and tissue plasminogen activator for treatment of ischemic stroke.

Neuroprotection against cerebral ischemia/reperfusion injury by intravenous administration of liposomal fasudil.

Fasudil, a Rho-kinase inhibitor, is a promising neuroprotectant against ischemic stroke; however, its low bioavailability is an obstacle to be overcome. Our previous study revealed that the liposomal drug delivery system is a hopeful strategy to increase the therapeutic efficacy of neuroprotectants. In the present study, the usefulness of intravenously administered liposomal fasudil for cerebral ischemia/reperfusion (I/R) injury treatment was examined in transient middle cerebral artery occlusion (t-MCAO) rats. The results showed that PEGylated liposomes of approximately 100nm in diameter accumulated more extensively in the I/R region compared with those of over 200nm. Confocal images showed that fluorescence-labeled liposomal fasudil was widely distributed in the I/R region, and was not noticeably taken up by microglia, which are well-known resident macrophages in the brain, and neuronal cells. These data indicated that liposomal fasudil mainly exerted its pharmacological activity by releasing fasudil from the liposomes in the I/R region. Moreover, liposomal fasudil effectively suppressed neutrophil invasion and brain cell damage in the t-MCAO rats, resulting in amelioration of their motor function deficits. These findings demonstrated both the importance of particle size for neuroprotectant delivery and the effectiveness of liposomal fasudil for the treatment of cerebral I/R injury.