New Drug Therapeutics to Prevent Noise-Induced Hearing Loss
We all know that loud noise can cause hearing loss. There is a great deal of research on how this occurs on a biochemical level, yet science has so far not provided us with good options for protecting our hearing except for the use of earplugs or earmuffs.
The problem most people face with earplugs or muffs is discomfort. Also, many people work on jobs that require the ability to hear spoken words despite being exposed to periodic, sudden, loud sounds.
Imagine a machinist who works in a factory. For safety reasons, that worker may need to be able to hear his/her coworkers and discuss the fine details of a piece of work being planned. Then, quite suddenly, there is a loud BANG! A coworker has just slammed a large piece of metal onto a machine for cutting. Unfortunately, this can expose everyone close to him/her to sufficient noise levels to cause damage to their hearing.
Of course, it is not always the first exposure to a loud sound that causes damage. But if there are repeated exposures, over time, then permanent changes in hearing can occur.
And, aside from affecting communication, noise-induced hearing loss can result in permanent problems with tinnitus (ringing or other noises in the ear) and discomfort with everyday sounds.
This is why it is important to look at alternative options for preventing noise-induced hearing loss. There is some promising new research on this topic.
How Noise Causes Hearing Loss
Sound is essentially the propagation of pressure waves, traveling through the air, which vibrate the ear drum, the ossicles (middle ear bones), and eventually, the delicate sensory cells (stereocilia) inside the cochlea. Once these sensory cells vibrate, they send electronic-like signals to a nerve called the “auditory nerve” or the 8th cranial nerve. From there, the brain does the work in decoding these signals, turning sound pressure waves traveling through the air into what we call “sound.”
There are many ways a person can acquire hearing loss. However, noise-induced hearing loss is typically caused by extremely powerful pressure waves, measured in decibels (dB), that directly injure those delicate sensory cells in the cochlea.
It is a myth that loud noise damages the ear drum. Only an actual explosion would be powerful enough to do that. More commonly, it’s everyday sounds that do the damage. This includes sounds from movie theatres, music concerts, use of power tools, shooting guns, or working in loud factories. In the modern world, it seems there is an exhaustive list of possible sources of loud noise.
This may sound overly simplistic. In actuality, the mechanism of how the ear undergoes damage from noise is much more complex… at least on a biochemical level. And this becomes more important when considering how moderate noise levels, over a long period of time, can also result in permanent hearing damage and tinnitus.
New Drug Therapeutics Under Investigation to Prevent Hearing Loss
As mentioned, ear plugs and muffs are effective, though sometimes uncomfortable, and inconvenient, tools for protecting hearing.
For people who cannot wear hearing protection on their job, or for people who just simply will not wear such devices due to discomfort, there needs to be another type of intervention.
What is being researched now are medicinal therapeutics (drugs) that can either be used to help prevent cochlear damage from noise exposure or can be used after exposure to lessen the long-term damage.
In 2017, Su-Hua Sha and Jochen Schacht published a review of the literature on therapeutics to treat and/or prevent noise-induced hearing loss. These investigators looked at the majority of quality published studies on this topic, and they offered some clarity on where the research is at this time.
Below is a table that summarizes the classifications of drugs, their mechanisms of action, drug names, and remarks made by these investigators.
| Classification | Mechanism of Action | Drugs | Remarks |
| Antioxidants | Reduce the production of reactive oxygen species and free radicals | N-acetyl cysteine* Glutathione, D-methionine, ebselen, resveratrol, etc. | N-acetyl cysteine is most evaluated. It provided pre and post-exposure protection to loud sounds in animals. *Also tested in human trials |
| Neurotrophic factors | Reduce the production of reactive oxygen species, manage calcium within the cells, and stop cells from committing suicide after injury | Glial cell-line- derived Neurotrophic factor (GDNF) | Protective at lower doses, hazardous at higher doses as it then augments loud sounds effects |
| Calcium channel blockers | Reduce calcium levels in the cochlear fluid | Verapamil Amlodipine etc. | Successful trials as they reduced calcium overload |
| Vasodilators | Increases blood blow to the cochlea, prevents cell suicide, reduces free radicals | Magnesium | Supportive evidence as the hearing improved in guinea pigs with a magnesium-rich diet Also tested in human trials |
| Steroid Hormones | Reduces swelling of injured hair cells, promotes healing | Dexamethasone Dehydro- epiandrosterone | Lessened the incidence of NIHL in animals |
| Anti- apoptotic agents | Reduces the tendency of hair cells to commit suicide after injury to loud sounds | Vitamin A AM- 111 | Huge potential to prevent NIHL with promising results Also tested in human trials |
In conclusion, the investigators, Sha and Schacht, state that there are some promising results coming from the studies they investigated. They say that “although no clinically applicable intervention has been approved yet, recent trials (drug studies) are encouraging.” They go on to say that it is likely viable treatments for noise-induced hearing loss will be commonly available within a decade.
Right Now, a Healthy Diet is the Best “Drug” Available
As one can tell from looking at the table above, there is already a significant amount of research being done on various therapeutics for treating and possibly preventing, noise-induced hearing loss.
In addition to these studies, there is considerable research being done that looks at the relationship between diet and hearing loss. [Click here for an article on diet and hearing loss] Research on this topic has shown that a healthy diet, one full of antioxidants from fresh fruits and vegetables, is also thought to be protective against noise-induced hearing loss.
Check this website for more information. As new research is published on this topic, we will be sure to keep you informed.
More Research on Drug Therapeutics to Prevent Noise-Induced Hearing Loss is Critical
Loud noise is a public health risk and it’s contributing to increases in the numbers of people with hearing loss, of all ages.
It is of utmost importance to know your risk. It’s imperative to know what noises cause damage, how to measure noise levels with a smartphone (or other devices), and how to best protect yourself. More and more young people are using earphones for extended periods of time, and this too is leading to increased rates of hearing loss.
If researchers can develop new therapeutics that can prevent or treat noise-induced damage, this will lead to yet another method of defense against modern noise.
By staying informed, you will know what options you have available to protect your hearing or the hearing of someone you love.
