Table 2.
Completed clinical trials of interventions for NIHL registered at ClinicalTrials.gov with reported results.
| ClinicalTrial.gov ID/Name |
Intervention | Study Design | Population, N | Active Arm, N | Comparator Arm, N | Primary Outcome | Secondary Outcomes | Results | Publication | Sponsor |
|---|---|---|---|---|---|---|---|---|---|---|
| NCT02903355: Phase 3 Clinical Trial: D-methionine to Reduce Noise-Induced Hearing Loss (NIHL) | D-methionine to prevent NIHL or tinnitus in a military population | Phase 3 RCT | US drill sergeant instructor trainees (21–45 y) receiving weapons training, N = 266 | 18 days of oral D-methionine, n = 124 | Placebo, n = 142 | ASHA shift from baseline to day 29–36 post-drug (day 15–22 post-noise exposure) | Change in DOEHRS-HC, EWS STS, THI | D- methionine was not superior to placebo on any outcome in the interim analysis | None | Metamor, Inc., USA [discontinued development] |
| NCT00808470: Micronutrients to Prevent Noise-induced Hearing Loss | Micronutrients to reduce magnitude of TTS from 4 h of loud music in young adults | Phase 2 RCT | Adults (18–35 y) with normal hearing, N = 70 | 4 days of oral beta carotene, vitamins C and E, magnesium, n = 35 | Placebo, n = 35 | Mean threshold shift at 4 kHz in both ears 15 min post-music vs. baseline | Threshold shift at 0.25, 0.5, 1, 2, 3, 6, and 8 kHz post-music; change in DPOAE amplitude, PMTF thresholds, and tinnitus measures | Micronutrients were not superior to placebo on any outcome in the final analysis | LePrell et al., 2016 [291] | University of Michigan, USA |
| NCT00552786: Antioxidation Medication for Noise-induced Hearing Loss | NAC to prevent TTS in workers exposed to noise in Taiwan | Randomized Phase 2 crossover | Males (25–65 y) with known work noise exposure, N = 53 | 14 days of 1200 mg NAC | Glucose capsule | Threshold shift from baseline measured with PTA, four time-spaced assessments | Threshold shift from baseline measured with DPOAE, four time-spaced assessments | NAC significantly reduced TTS among men without any GSTIM1 or GSTT1 polymorphisms | Lin et al. (2010) [300] | National Taiwan University Hospital, Taiwan |
| NCT02951715: Improvement of Tinnitus After Oral Zinc on Patients With Noise-induced Hearing Loss | Zine to improve NIHL and tinnitus symptoms | Open label, single arm | Adults with confirmed NIHL-related tinnitus, N = 20 | 2 months of 40 mg oral zinc daily | None | THI change from baseline | Threshold shift, speech discrimination, DPOAE, tinnitus pitch/loudness from baseline | Zinc did not significantly improve hearing threshold but did improve THI score from baseline | Yeh et al. (2019) [296] | Chang Gung Memorial Hospital, China |
| NCT01444846: Otoprotection With SPI-1005 for Prevention of Temporary Auditory Threshold Shift | Ebselen to prevent TTS | Phase 2 RCT | Adults (18–31 y) with normal hearing, N = 83 | 4 days of oral 200, 400, or 600 mg ebselen, total n = 63 | Placebo capsule, n = 20 | Reduction in TTS from baseline (15 min post-sound exposure) at 4 kHz | N/A | Significant reduction in TTS at 4 kHz in 400 mg ebselen vs. placebo groups | Kil et al. (2017) [309] | Sound Pharmaceuticals, Inc., USA |
Abbreviations: ASHA, American Speech-Language-Hearing Association; dB, decibel; DOEHRS-HC, Defense Occupational and Environmental Health Readiness System-Hearing Conservation; DPOAE, distortion product otoacoustic emissions; EWS, early warning shift; h, hour; kHz, kilohertz; min, minutes; NAC, N-acetylcysteine; NIHL, noise-induced hearing loss; PMTF, psycho-acoustical modulation transfer function; RCT, randomized controlled trial; STS, standard threshold shift; THI, Tinnitus Handicap Inventory; TTS, temporary threshold shift; US, United States; y, year.