In vitro release kinetics of gentamycin from a sodium hyaluronate gel delivery system suitable for the treatment of peripheral vestibular disease

For certain patients who experience intense vertigo arising from unilateral vestibular lesions, the primary therapy is a vestibular nerve section an i ntracranial surgical procedure. One alternative to this treatment is therap eutic ablation of vestibular function on the unaffected side using an ototo xic agent. We prepared a biodegradable sustained-release gel delivery syste m using sodium hyaluronate that can be administered into the middle ear usi ng only a local anesthetic. The gel contains gentamycin sulfate, the ototox ic agent of choice for treatment of unilateral vestibulopathy, and it exhib its diffusion-controlled release of the drug over a period of hours. The re leased gentamycin could then diffuse into the inner ear through the round m embrane. This represents an important advance over previous formulations, w hich used only gentamycin sulfate solutions, in that it should allow more c areful control of the dose, it should reduce loss of the drug from the midd le ear site, and it should maintain intimate contact with the round membran e. By carefully controlling the dose, it should be possible to inhibit vest ibular function while minimizing hearing loss. Herein we describe the in vi tro release kinetics of gentamycin sulfate from sodium hyaluronate gels and find that the system obeys Fickian behavior.