The protective effect of erdosteine against ototoxicity induced by cisplatin in rats

The elimination of cisplatin ototoxicity is an ongoing concern. This experimental study was undertaken to investigate the effect of oral erdosteine in ameliorating cisplatin-induced ototoxicity. Twenty-eight adult female Wistar albino rats were randomly divided into four equal groups. Group A received an oral carrier vehicle of the drug erdosteine with 0.2 ml of 0.9% saline. Group B was administered only erdosteine (per oral 10 mg/kg twice a day) for 6 days. Group C was injected with cisplatin intraperitoneally (i.p.) on day 0 (16 mg/kg body weight), once only. Group D was given erdosteine (per oral 10 mg/kg/day) 1 day before and for 5 days consecutively after cisplatin injection (16 mg/kg, i.p.). Distortion product otoacoustic emissions (DPOAEs) were elicited in different frequency regions, ranging from 1,001 to 6,299 Hz as DPgram and input/output (I/O) functions from the control and experimental animals. All experimental animals were killed under general anesthesia on day 5, following the last otoacoustic emission measurements. Prior to death, blood samples were drawn for measurement of superoxide dismutase, xanthine oxidase (XO), malondialdehyde and nitric oxide. Initial DPgram and I/O function baseline measurements were similar in all groups prior to any drug administration ( P>0.05). On day 5, intra-subject measurement parameters of DPgrams and I/O functions in the cisplatin group showed significant deterioration ( P <0.05). The other groups revealed no differences between their pre- and post-test drug administration DPgrams and I/O functions at any test frequency ( P>0.05). Comparison of the amplitudes of DPgrams and I/O functions between the cisplatin and control groups showed significant changes ( P <0.05). Biochemical studies noted an increased XO activity following cisplatin administration ( P <0.007). The other biochemical results did not show significant differences between the study and control groups. This study demonstrates that, in rats, erdosteine is protective for cochlear function against the disruptive effects of cisplatin as measured by DPOAEs.