Intracochlear, biodegradable implants for controlled release of glucocorticoids

Background Effective local drug delivery to the inner ear is a major goal for efficient treatment of inner ear diseases. Direct intracochlear drug application would overcome disadvantages of systemic and intratympanic treatment i.e., effects of the blood-labyrinth and the round window membrane barrier.

Methods Intracochlear PLGA- or PEG-PLGA-based implants containing dexamethasone or triamcinolone were prepared by hot-melt extrusion. Mechanical properties and drug release profiles were investigated. Simulations of drug distribution in the perilymph of human scala tympani were performed with FluidSim V4.05 based on the in vitro drug release kinetics. Implants were tested for implantation into the scala tympani of human temporal bones through round window insertion and investigated with “postsurgical” ultra-high-resolution computed tomography (micro-CT).

Results Implants based on PEG-PLGA reached an improved mechanical stability, which will ease the handling and intracochlear application. In vitro release studies of the implants and mathematical simulations of the pharmacokinetics in the human inner ear indicated higher achievable maximum drug concentrations and a more apical spread of triamcinolone compared to dexamethasone. The general feasibility of using implants alone or in co-administration with a cochlear implant array was demonstrated with micro-CT of the temporal bones.

Conclusions We demonstrated the possibility of administering implants with controlled release characteristics independent of the use of a cochlear implant. The drug delivery system provides the option of varying drugs and concentrations through the manufacturing process. This combination of drug therapy and a medical device can thus contribute to personalized medicine in hearing rehabilitation.

Publication History

Article published online:
12 May 2023