Full Text Available There are several challenges to inner ear drug delivery and imaging due to the existence of tight biological barriers to the target structure and the dense bone surrounding it. Advances in imaging and nanomedicine may provide knowledge for overcoming the existing limitations to both the diagnosis and treatment of inner ear diseases. Novel techniques have improved the efficacy of drug delivery and targeting to the inner ear, as well as the quality and accuracy of imaging this structure. In this review, we will describe the pathways and biological barriers of the inner ear regarding drug delivery, the beneficial applications and limitations of the imaging techniques available for inner ear research, the behavior of engineered nanomaterials in inner ear applications, and future perspectives for nanomedicine-based inner ear imaging.
Liu, Xu; Li, Mingshuang; Smyth, Hugh; Zhang, Feng
Disorders of the ear severely impact the quality of life of millions of people, but the treatment of these disorders is an ongoing, but often overlooked challenge particularly in terms of formulation design and product development. The prevalence of ear disorders has spurred significant efforts to develop new therapeutic agents, but perhaps less innovation has been applied to new drug delivery systems to improve the efficacy of ear disease treatments. This review provides a brief overview of physiology, major diseases, and current therapies used via the otic route of administration. The primary focuses are on the various administration routes and their formulation principles. The article also presents recent advances in otic drug deliveries as well as potential limitations. Otic drug delivery technology will likely evolve in the next decade and more efficient or specific treatments for ear disease will arise from the development of less invasive drug delivery methods, safe and highly controlled drug delivery systems, and biotechnology targeting therapies.
Full Text Available Fibrous tissue growth and loss of residual hearing after cochlear implantation can be reduced by application of the glucocorticoid dexamethasone-21-phosphate-disodium-salt (DEX. To date, sustained delivery of this agent to the cochlea using a number of pharmaceutical technologies has not been entirely successful. In this study we examine a novel way of continuous local drug application into the inner ear using a refillable hydrogel functionalized silicone reservoir. A PEG-based hydrogel made of reactive NCO-sP(EO-stat-PO prepolymers was evaluated as a drug conveying and delivery system in vitro and in vivo. Encapsulating the free form hydrogel into a silicone tube with a small opening for the drug diffusion resulted in delayed drug release but unaffected diffusion of DEX through the gel compared to the free form hydrogel. Additionally, controlled DEX release over several weeks could be demonstrated using the hydrogel filled reservoir. Using a guinea-pig cochlear trauma model the reservoir delivery of DEX significantly protected residual hearing and reduced fibrosis. As well as being used as a device in its own right or in combination with cochlear implants, the hydrogel-filled reservoir represents a new drug delivery system that feasibly could be replenished with therapeutic agents to provide sustained treatment of the inner ear.
Dai, Juan; Long, Wei; Liang, Zhongping; Wen, Lu; Yang, Fan; Chen, Gang
Delivery of biomacromolecular drugs into the inner ear is challenging, mainly because of their inherent instability as well as physiological and anatomical barriers. Therefore, protein-friendly, hydrogel-based delivery systems following local administration are being developed for inner ear therapy. Herein, biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) containing interferon α-2 b (IFN α-2 b) were loaded in chitosan/glycerophosphate (CS/GP)-based thermosensitive hydrogel for IFN delivery by intratympanic injection. The injectable hydrogel possessed a physiological pH and formed semi-solid gel at 37 °C, with good swelling and deswelling pr