[The role of the inner ear biological barrier in targeted drug delivery for inner ear diseases].

The endolymphatic barrier, composed of tight junctions and ion transporters, regulates the ionic gradient between endolymph and perilymph and plays a pivotal role in maintaining inner ear function. Disruption of this biological barrier can result in ionic imbalance, causing both auditory and vestibular dysfunction. Medication needs to enter the perilymph instead of the endolymph by passing through the perilymphatic barrier to reach the hair cells. Targeted drug delivery has emerged as a promising therapeutic strategy for inner ear diseases, including intratympanic injection, intracochlear infusion, and molecularly targeted delivery systems. Intratympanic injection increases drug concentration in the perilymph while minimizing systemic side effects. Molecularly targeted approaches enable precise drug delivery to hair cells, spiral ganglion neurons, etc., thereby enhancing therapeutic efficacy. Future research should focus on improving targeting specificity to facilitate clinical translation for inner ear disease treatment. The current article systematically elucidates the key anatomical and physiological characteristics of the inner ear, the mechanisms of its biological barriers, and pathological damage under disease conditions, with a primary focus on discussing the strategies and prospects for targeted inner ear drug delivery.