RESUMO
The authors present the development of a new device that consists of a biodegradable support matrix incorporating a therapeutically releasable amount of ampicillin. This device is in an insertable shape that allows easy placement into the middle ear. Once in the middle ear cavity it expands, contacts the walls, and provides extended sustained release of ampicillin. In vitro studies over three months documented the consistent release of therapeutically effective levels of ampicillin. In vivo efficacy was demonstrated in the cat otitis media induced by eustachian tube obstruction. Cultures of normal cat middle ear cavities prior to obstruction revealed no microflora. Cultures after obstruction of the middle ears of animals treated with this device had no growth of bacteria as early as one week after obstruction (10 out of 12 cats). The contralateral untreated ears became culture negative at two weeks post obstruction, suggesting that the effect of the device is not limited to the treated ear. Histopathological studies showed the effect of the device as early as one week post obstruction in treated ears and after two weeks in the contralateral ear. Both ears became normal at three months, while obstructed untreated animals (controls) developed chronic irreversible otitis media changes. In addition, histopathological findings documented a lack of inflammatory reaction from the device itself, and its capacity of being biodegradable. Topical extended middle ear drug delivery can become a significant form of treatment for middle ear disease and has the potential of being useful as a source for inner ear drug delivery.
