[Ototoxicity study of netilmicin in pregnant guinea pigs and the embryo].

The ototoxicity of netilmicin (NTL) in pregnant guinea pigs (Hartley strain) and the newborn was examined and compared to that of gentamicin (GM). NTL was administered intramuscularly at dose of 90 mg/kg to pregnant guinea pigs from day 0 to day 35 of pregnancy (the early period of pregnancy) or from day 42 of pregnancy to 1 day prior to delivery (the late period of pregnancy). GM at dose of 45 mg/kg or physiological saline were administered intramuscularly to pregnant guinea pigs during the late period of pregnancy. Four of 5 dams given NTL during the early period of pregnancy, 4 of 7 dams given TNL during the late period of pregnancy, and 2 of 4 dams given GM during the late period of pregnancy died. No pinna reflex loss in frequency range from 2 to 20 KHz were detected in mother guinea pigs treated with NTL either during the early period of pregnancy or during the late period of pregnancy. GM caused a loss of pinna reflex at 20 KHz in mother guinea pigs treated during the late period of pregnancy. Histopathologically, no damages were detected in the cochlea of mother guinea pigs treated with NTL during the early or late period of pregnancy, whereas slight scattered loss of hair cells was seen in the vestibulum. However, GM at dose of 45 mg/kg, caused an incomplete scattered loss of outer hair cells in the spiral organ, moderate atrophy of the spiral ganglion cells and a partial loss of hair cells in the vestibular organs in mother guinea pigs treated during the late period of pregnancy. In newborn guinea pig from the pregnant one treated with NTL during the early period of pregnancy, there was no loss of pinna reflex. The same results were obtained in newborn guinea pigs from the pregnant ones treated with either NTL or GM during the late period of pregnancy. No histopathological damages were detected. The present study suggests that NTL has a minimal effect on the auditory and vestibular organs in pregnant guinea pigs and the newborn and is considered to be 1 of the aminoglycosides with low ototoxic potential.