Evaluation of the protective effect of α-lipoic acid on cisplatin ototoxicity using distortion-product otoacoustic emission measurements: an experimental animal study.

The aim of our study was to determine the effectiveness of intratympanic α-lipoic acid injection as an otoprotective agent against cisplatin-induced ototoxicity in guinea pigs. Twenty-four adult male albino guinea pigs with normal hearing were divided into 4 groups. The guinea pigs received intraperitoneal cisplatin in group 1, intraperitoneal cisplatin and intratympanic α-lipoic acid in group 2, intratympanic α-lipoic acid in group 3, as well as intraperitoneal cisplatin and intratympanic saline in group 4. Distortion-product otoacoustic emission measurements were obtained for both ears at the following time points: before administration (baseline recording) and on day 3 (72 h later). In group 1 (cisplatin), significant deterioration was observed at all frequencies on day 3 (P < 0.05). In group 2 (cisplatin + α-lipoic acid), deterioration was observed at all frequencies on day 3; however, this deterioration did not reach a statistical significance (P > 0.05). In group 3 (α-lipoic acid), no significant difference was observed between baseline and day 3 (P > 0.05). In group 4 (cisplatin + saline), deterioration was observed at all frequencies on day 3; however, this deterioration did not reach a statistical significance (P > 0.05). Cisplatin-induced hearing loss in the guinea pigs may be limited to some extent by the concomitant use of α-lipoic acid. Dose-dependent changes in the possible effects of α-lipoic acid need further investigation. Future morphologic studies may contribute to expose clearly the protective effect of α-lipoic acid.