Auditory effect of kanamycin given to newborn guinea pigs whose mothers received kanamycin during pregnancy.

Clinical and experimental data indicate that aminoglycoside ototoxicity occurs more frequently in individuals previously exposed to ototoxic drugs. This study investigated the auditory effect of repetitive administration of kanamycin on newborn guinea pigs that had previously been exposed, in utero, to kanamycin administered to their mothers. Sixteen pregnant guinea pigs in the late stages of gestation were divided into two groups, one receiving kanamycin 500 mg/kg per day intramuscularly for 8 days, and the other acting as a control. After birth, the mothers and their newborns in both groups were examined for auditory brain stem response (ABR) and then treated with kanamycin 500mg/kg per day for 4 days. The results from the second examination demonstrated that the group receiving prior treatment with kanamycin, despite their good ABR responses during the first measurement, showed significantly elevated auditory thresholds compared to the control group. Therefore, any ototoxic drugs should be used with extreme caution in newborns having had prior exposure to the drugs in utero, even if they have a "normal" auditory response after birth.