Localized drug delivery to the middle ear: Recent advances and perspectives for the treatment of middle and inner ear diseases

Traditionally, the majority of ototopical delivery systems are conventional medicated ear drops. However, their endurance and wide utility is jeopardized due to the presence of an assortment of anatomical obstacles to the ear delivery. The growing knowledge of physiology and anatomy of ear and ear diseases paves the way to the critical design of auspicious delivery vehicles. Working on this concept, the prevalence of innovative nano-systems, in situ gels, otoimplants is vastly increased to transport bioactive in a prolonged manner and maximize their therapeutic competence. This review addresses ear anatomy, ear barriers impeding effective delivery and modes of localized delivery. Moreover, special focuses on middle and inner ear diseases and its targeted drug delivery systems, covering the applications of hydrogels and nanocarriers via localized delivery to middle ear. Extensive search in literature was done to gather information about these advanced systems, in terms of composition, application mode, in vitro and ex vivo efficacy assessment as well as therapeutic outcomes in animal models. Current advances in vehiculation of ear delivery are satisfying to be utilized in vivo, yet further endeavors still need to be extended to form custom-made marketed ear delivery platforms in industrial scale with respect to clinical efficacy, safety, and tolerability.