Abstract
Antibiotics which have ototoxicity should be carefully administered in clinical treatment. Patients with chronic otitis media are often treated by intratympanic therapy. Basic studies on ototoxicity, however, are rarely reported.
The present study was performed to examine the influence of intratympanic antibiotic administration on the internal ear in 46 guinea pigs (19 in the fosfomycin group, 17 in the gentamicin group, 10 in the physiological saline group as controls). Fosfomycin sodium solution of 0.2ml (6mg), gentamicin solution of 0.2ml (8mg) and physiological saline of 0.2ml were instilled daily into the tympanic cavity through a silicon tube at the back of the ear of the guinea pig for 10 days.
Electrocochleography (ECoG) was performed to examine the ECoG-threshold in the experimental animals and scanning electronmicroscopy (SEM) was also used to observe the extirpated cochlea after sacrifice. The ototoxicity of gentamicin was observed both functionally and morphologically to almost the same degree. On the other hand no ototoxicity of fosfomycin was noted.
The clinical significance and usefulness of topical administration into the tympanic cavity of these antibiotics are discussed briefly.
