Institute for Biomedical Engineering, University Medical Center Rostock, 18119 Rostock, Germany.
Department of Otorhinolaryngology, Head and Neck Surgery and Hearing4all Cluster of Excellence, Hannover Medical School, 30625 Hannover, Germany.
Molecules. 2022 Feb 19;27(4):1417. doi: 10.3390/molecules27041417.
Cochlear implants, like other active implants, rely on precise and effective electrical stimulation of the target tissue but become encapsulated by different amounts of fibrous tissue. The current study aimed at the development of a dual drug release from a PLLA coating and from the bulk material to address short-term and long-lasting release of anti-inflammatory drugs. Inner-ear cytocompatibility of drugs was studied in vitro. A PLLA coating (containing diclofenac) of medical-grade silicone (containing 5% dexamethasone) was developed and release profiles were determined. The influence of different coating thicknesses (2.5, 5 and 10 µm) and loadings (10% and 20% diclofenac) on impedances of electrical contacts were measured with and without pulsatile electrical stimulation. Diclofenac can be applied to the inner ear at concentrations of or below 4 × 10 mol/L. Release of dexamethasone from the silicone is diminished by surface coating but not blocked. Addition of 20% diclofenac enhances the dexamethasone release again. All PLLA coatings serve as insulator. This can be overcome by using removable masking on the contacts during the coating process. Dual drug release with different kinetics can be realized by adding drug-loaded coatings to drug-loaded silicone arrays without compromising electrical stimulation.
人工耳蜗等有源植入物依赖于对目标组织的精确和有效的电刺激，但会被不同量的纤维组织包裹。本研究旨在开发一种从 PLLA 涂层和本体材料中双重药物释放的方法，以解决短期和长期释放抗炎药物的问题。体外研究了内耳细胞对药物的相容性。开发了一种含有双氯芬酸钠的医用级硅酮（含有 5%地塞米松）的 PLLA 涂层，并确定了释放曲线。在有无脉动电刺激的情况下，测量了不同涂层厚度（2.5、5 和 10 µm）和载药量（10%和 20%双氯芬酸钠）对电接触阻抗的影响。双氯芬酸钠可以以低于或等于 4×10^-6mol/L 的浓度应用于内耳。硅酮中的地塞米松的释放虽然受到表面涂层的抑制，但并未被完全阻断。添加 20%双氯芬酸钠可再次增强地塞米松的释放。所有 PLLA 涂层都起到绝缘体的作用。在涂层过程中，通过在接触部位使用可移动的掩模可以克服这一问题。通过向载药硅酮阵列添加载药涂层，可以实现具有不同动力学的双重药物释放，而不会影响电刺激。
