Toxicology and applied pharmacology
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To study the possible age-dependent ototoxic effects of tobramycin a subacute toxicity study was performed. To young adult (3 months) and old (27-30 months) female Wag-Rij rats 0, 10, 40, and 160 mg tobramycin sulfate/kg was administered subcutaneously in two doses a day. After 14 days all animals were autopsied. ⋯ As old control rats showed already a large number of OHC without stereocilia, the possible ototoxic effects of tobramycin were not detected against this "background" of stereociliary loss, consistent with aging. The damage in old rats was certainly not greater than in young adult rats. In conclusion, old rats were not more sensitive to the possible ototoxic effects of tobramycin than young adult rats.