Therapeutic effects of orally administrated antioxidant drugs on acute noise-induced hearing loss

Abstract

Objective: The objective of this study was to investigate the dose-dependent therapeutic effect of the orally administrated antioxidant drugs [4-hydroxy alpha-phenyl-tert-butylnitrone (4-OHPBN) and N-acetyl-L-cysteine (NAC)] on acute noise-induced hearing loss because oral administration is the most commonly used method of drug administration due to its convenience, safety, and economical efficiency.

Methods: Thirty chinchilla were exposed to a 105 dB octave band noise centered at 4 kHz for 6 h and randomly assigned to a control group (saline only) and three experimental groups [4-OHPBN (10 mg/kg) plus NAC (20 mg/kg), 4-OHPBN (20 mg/kg) plus NAC (50 mg/kg), and 4-OHPBN (50 mg/kg) plus NAC (100 mg/kg)]. The drugs were orally administrated beginning 4 h after noise exposure and then administered twice daily for the next 2 days. Permanent auditory brainstem response threshold shifts, distortion product otoacoustic emission threshold shifts, and the percentage of missing outer hair cell were determined.

Results: The oral administration significantly reduced permanent hearing threshold shift, distortion product otoacoustic emission threshold shift, and the percentage of missing outer hair cell in a dose-dependent manner.

Discussion: This result demonstrates that orally administered drugs can treat acute noise-induced hearing loss in a dose-dependent manner. This suggests that oral administration was effective in treating acute noise-induced hearing loss as in intraperitoneal administration.