中药复方内耳给药系统的构建及递药机制研究

Drug delivery of traditional Chinese medicine (TCM) into the inner ear and the brain is made difficult by the presence of the blood-inner ear barrier(BIB) and blood-brain barrier(BBB). There is an increasing interest in the treatment of inner ear disorders or brain diseases by topical application of drugs to the inner ear. It's expected to be a breakthrough, which can bypass BIB and BBB.One of the most important issues to overcome before full clinical application is the development of smart delivery systems for drugs to the target sites and controlled release in the inner ear and the brain. The research of completed NSFC（30801553）showed that the effective components of TCM diffused through the round window membrane (RWM) into the perilymph in the inner ear and then transported to the cerebrospinal fluid (CSF) bypassing the BBB, and introcochlear administration could greatly improve drug distribution within the inner ear and the brain. Furthermore, nanoparticles(NP) which substantially increased local bioavailability, had significant sustained-release effect. Drugs or NP in the perilymphatic compartment might transport through the cochlear aqueduct and into CSF. However, NP also displayed the shortage as drugs carrier via inner ear administration. Derived from quality by design (QbD) and its experimental design, it needs further research for the formulations from more aspects in the present study. We will examine the properties of NP by means of in vitro experimental model for RWM, cochlear cultures and in vivo experiments of guinea pigs, with the cell, organism and animal level. Further, we will show the influence for cochlear cellular uptake, membrane permeation capacity and drug delivery in vivo, and the relationship between the properties of NP and distribution as well, and screen the appropriate nano-drug delivery system. Acting as TCM partner, salviae miltiorrhizae and panax notoginseng are going to be selected as model drugs. Nano- and biphasic drug delivery systems will be explored the capacity as introcochlear drug carriers loaded with the TCM partner, especially the transport mechanism through RWM. Based on our previous research, this study will open up a new research field on inner ear drug delivery system of TCM compound prescription and construct its theory. Besides, the study will supply scientific information for developing compound preparation of TCM and establish the foundation of exerting its therapeutic effect for TCM into the inner ear and the brain.

血-内耳屏障和血脑屏障限制了中药疗效的发挥。内耳（局部）给药能避开上述两种屏障的阻碍，将药物有效递送至内耳及脑。已完成的国家自然科学基金研究表明中药多组分采用内耳给药可经圆窗膜分布至内耳和脑，将其包载于纳米粒中可进一步改善递释效果，但也发现了普通纳米粒作为内耳给药载体的不足。"质量源于设计"，本项目拟在此基础上，从剂型角度深入研究，并提高研究层面，应用体外圆窗膜模型、体外培养耳蜗模型和豚鼠体内试验，在细胞、器官和动物水平上多层次考察纳米粒特性对耳蜗细胞摄取、经膜渗透、体内转运的影响及与分布的关系，筛选适宜的纳米系统；以药对丹参-三七有效组分为模型，深入探索纳米传递系统及与原位凝胶结合制成的双相释药系统，作为复方多组分内耳给药载体的潜力，考察其递药机制。结合前期研究，构建比较系统的中药复方内耳给药系统的理论体系，丰富中药制剂的研究内容，为中药进入内耳或脑内充分发挥治疗作用奠定基础。

由于血-内耳屏障和血脑屏障的存在，药物采用常规方式难以有效进入内耳或脑部。从解剖生理来看，内耳与机体其他部位隔离，特别适合局部给药。我们前期研究发现，内耳（局部）给药能使药物经圆窗膜直接进入内耳外淋巴，并转运至脑脊液，从而避开血-内耳屏障和血脑屏障的阻碍。不过，对于内耳给药来说，中耳清除将极大影响药物在内耳的浓度与作用时间，这就要求人们研究和发展新的药物传递系统，以努力克服其不利影响和限制。本项目从经典药对丹参-三七的有效组分着手，以PLGA纳米粒为载体，将现代医学理论和制剂新技术引入中药复方组分研究，构建中药复方内耳给药系统新模式。“质量源于设计”，本项目从剂型角度深入研究，制备了不同特性（不同粒径及表面修饰）的PLGA纳米粒，探索其透过圆窗膜的转运通路及体内分布规律，首次阐明了纳米粒经圆窗膜的跨膜转运机制，揭示了纳米粒的表面性质对其耳蜗毛细胞摄取及体内转运的影响，为优化设计纳米递药系统，提高药物疗效奠定了基础。设计和制备包载丹参-三七有效组分的PLGA纳米传递系统，考察其经内耳给药的体内转运特征与机制，结果显示PLGA纳米载体能有效携载中药复方多组分至内耳及脑部，提高局部生物利用度。并且，为进一步克服中耳清除的影响，本项目还将PLGA纳米粒负载于温度敏感原位凝胶制成双相释药系统，结果发现双相释药系统不仅能有效携载中药复方多组分穿过圆窗膜，提高局部生物利用度，还能延长药物的体内滞留时间。此外，药效学和初步毒性评价表明，丹参-三七复方组分内耳纳米给药系统对老年性耳聋或脑缺血有一定的防治作用，不会引起内耳功能损伤。综上所述，该研究结果不仅为内耳纳米给药系统的设计提供理论指导，也为中药复方内耳给药制剂的研发提供技术支撑与参考，具有较高的学术价值和应用前景。