For certain patients who experience intense
vertigo arising from unilateral vestibular lesions, the primary
therapy is a vestibular nerve section, an intracranial
surgical procedure. One alternative to this treatment is therapeutic ablation of vestibular function on the unaffected side using an ototoxic agent. We prepared a biodegradable sustained-release gel delivery system using
sodium hyaluronate that can be administered into the middle ear using only a
local anesthetic. The gel contains
gentamycin sulfate, the ototoxic agent of choice for treatment of unilateral vestibulopathy, and it exhibits diffusion-controlled release of the
drug over a period of hours. The released
gentamycin could then diffuse into the inner ear through the round membrane. This represents an important advance over previous formulations, which used only
gentamycin sulfate solutions, in that it should allow more careful control of the dose, it should reduce loss of the
drug from the middle ear site, and it should maintain intimate contact with the round membrane. By carefully controlling the dose, it should be possible to inhibit vestibular function while minimizing
hearing loss. Herein we describe the in vitro release kinetics of
gentamycin sulfate from
sodium hyaluronate gels and find that the system obeys Fickian behavior.