Antioxidants and Vasodilators for the Treatment of Noise-Induced Hearing Loss: Are They Really Effective?

Abstract

We live in a world continuously immersed in noise, an environmental, recreational, and occupational factor present in almost every daily human activity. Exposure to high-level noise could affect the auditory function of individuals at any age, resulting in a condition called noise-induced hearing loss (NIHL). Given that by 2018, more than 400 million people worldwide were suffering from disabling hearing loss and that about one-third involved noise over-exposure, which represents more than 100 million people, this hearing impairment represents a serious health problem. As of today, there are no therapeutic measures available to treat NIHL. Conventional preventive measures, including public awareness and education and physical barriers to noise, do not seem to suffice, as the population is still being affected by damaging noise levels. Therefore, it is necessary to develop or test pharmacological agents that may prevent and/or diminish the impact of noise on hearing. Data availability about the pathophysiological processes involved in triggering NIHL has allowed researchers to use compounds, that could act as effective therapies, by targeting specific mechanisms such as the excess generation of free radicals and blood flow restriction to the cochlea. In this review, we summarize the advantages/disadvantages of these therapeutic agents, providing a critical view of whether they could be effective in the human clinic.

Effect of Phlorofucofuroeckol A and Dieckol Extracted from Ecklonia cava on Noise-induced Hearing Loss in a Mouse Model

“…Antioxidants protect against NIHL [ 24 , 25 ]. Diverse antioxidants, including N-acetyl-L-cysteine (NAC), acetyl-L-carnitine (ALCAR), 4-hydroxy alpha-phenyl-tert-butylnitrone (4-OHPBN), salicylate, 2,4-disulfonyl a-phenyl tertiary butyl nitrone (HPN-07), HK-2, and others, show protective effect against noise-induced damage in the cochlea [ 26 , 27 , 28 , 29 , 30 ].…”

Protective effects of vitamins/antioxidants on occupational noise-induced hearing loss: A systematic review

“…Also, Jung et al, in their review study in the field of association between nutritional factors with hearing loss, found that various nutritional factors (such as vitamins A, C, and E, and zinc) are associated with hearing status, and the incidence of hearing loss was increased with the lack of these micronutrients 30 . Alvarado et al in their study showed that combination of some or all of the antioxidants, such as NAC, vitamins A, C, and E, and magnesium (Mg), can affect on their mechanisms of action, potentiating the optimistic effect over noise overexposure 31 …”

“…However, according to our search results, so far no study has been done to systematically review the relationship between vitamins/antioxidants on occupational NIHL. Only, Alvarado et al in their review on a small number of studies showed that combination of some or all of the antioxidants, such as NAC, vitamins A, C, E, and magnesium (Mg), can produce synergism and/or redundancy in their mechanisms of action, potentiating the positive effect over noise overexposure, and also considered these otoprotective agents as a hopeful new therapeutic strategy for ameliorating, delaying, or even preventing the impact of noise on hearing 31 . So, the current study is conducted to systematically review the protective effects of vitamins/antioxidants on occupational NIHL.…”

Safety and Efficacy of Intratympanic Alpha-Lipoic Acid Injection in a Mouse Model of Noise-Induced Hearing Loss

“…Additionally, most animal studies investigating the effect of ALA on the cochlea have used drug-induced hearing loss models [ 10 , 11 , 14 , 15 ]. Acoustic trauma triggers inflammatory reactions, oxidative stress, and insufficient blood supply to the inner ear, leading to apoptosis of sensory cells [ 18 ]. Several antioxidants, such as glutathione and N-acetylcisteine, have been studied to target oxidative stress, and have been reported to have an oto-protective effect against NIHL [ 18 , 19 , 20 ].…”