Ototoxicity of tobramycin, gentamicin, amikacin and sisomicin in the guinea pig

Abstract

A significant side effect of aminoglycoside antibiotics is permanent hearing loss. This study was designed to determine the relative ototoxic liability of tobramycin, gentamicin, amikacin, and sisomicin. These drugs were given in daily subcutaneous dosages of 0, 50, 100, 150 or 200 mg/kg to guinea pigs for 4 weeks. Auditory damage was assessed by determining the Preyer pinna reflex, the ability of the cochlea to generate the AC cochlear potential and the number of sensory hair cells missing from the organ of Corti. Concentrations of antibiotic were determined in plasma and perilymph by a radioenzymatic assay. On an equal-dose basis the ototoxic liability of gentamicin was found to be similar to that of sisomicin, whereas the ototoxic liability of tobramycin was found to be similar to that of amikacin. Tobramycin and amikacin were less ototoxic than gentamicin and sisomicin.