Investigation of the Protective Efficacy of Intratympanic Dexamethasone and Nimodipine on Cisplatin Ototoxicity in a Rat Model

Abstract

Objective: To investigate and compare the levels of efficacy of dexamethasone and nimodipine that are known for their neuroprotective properties on cisplatin ototoxicity in a rat model. Methods: The study included 24 male Wistar Albino rats that generated distortion product otoacoustic emission (DPOAE) response. The rats were randomized into three groups. Group 1 (n=8) was taken as the Control Group and administered intraperitoneal cisplatin at a dose of 5 mg/kg on days 1, 3 and 5, adding to a cumulative dose of 15 mg/kg in total. Afterwards, intratympanic saline solution of 0.1-0.3 ml was administered on days 5, 10 and 15. In Group 2 (n=8) the same cisplatin protocol was used followed by intratympanic dexamethasone administered on days 5, 10 and 15 at a dose of 0.1-0.3 ml. In Group 3 (n=8) the same cisplatin protocol was used followed by intratympanic nimodipine administered on days 5, 10 and 15 at a dose of 0.1-0.3 mL. In all groups DPOAE was measured before (Day 1) and after (Day 5) cisplatin administration and after intratympanic treatment (Day 20). After the final measurement all rats were sacrificed and histopathologically examined. The study complied with the guidelines for the care and utilization of animals set forth by the Declaration of Helsinki. Results: Cisplatin have caused hearing loss at all frequencies, with more significance at higher frequencies (p