Oklahoma research may lead to prevention of hearing loss
Rather than wearing hearing aids, people may soon simply put drops in their ears to prevent the hearing damage in the first place, if Oklahoma scientists’ research progresses as expected.
Two combined compounds are preventing inner ear damage that causes hearing loss, indicate lab- oratory experiments by Robert Floyd, an Oklahoma Medical Research Foundation researcher, and Dr. Richard Kopke, a retired Army ear surgeon
and Hough Ear Institute chief executive.
The compounds, 4OHPBN nitrone and n-acetyl-cysteine, appear to stop hearing loss caused by loud noises.
“We were able to show that if we get the combination of the compounds in about four hours after the exposure, we can almost completely protect from hearing loss, about 80 to 90 percent,” Floyd said.
Timing the medication seems to be important. If 12 hours pass before the compounds are injected, the researchers found they could reduce hearing loss by up to 50 percent.
It’s a significant issue because noise-induced hearing loss is the most common cause of nerve deafness worldwide, Kopke said. About 30 million Americans are exposed to excessive noise in the workplace, and about 200 million suffer worldwide. About 48 million Americans age 12 and older have trouble with daily communication because of hearing loss, according to new research by the Johns Hopkins School of Medicine.
“If this is successful in clinical trials and people adopted its use, it could have a major impact on decreasing deafness worldwide ... So, there would be fewer people with hearing aids,” Kopke said.
He said his military experience partially motivated him to get into hearing loss research as he watched troops reassigned and their lives changed by hearing loss caused by aircraft, weapons systems and combat duty. The troops use ear plugs, but hearing damage still is one of the primary disabilities of those returning from Iraq and Afghanistan, he said.
“They’re in their 20s or 30s with the hearing of a 70-year-old,” Kopke said.
The research on lab chinchillas and rats turned up several surprising findings. They discovered that the hearing in treated animals continued to improve for six months after receiving the medication, while untreated animals showed no improvement or worsened after six months. Also, when com- bined, one compound had a therapeutic effect on the outer hair cells, while the other appeared to restore the nerve endings.
Also, in simulated explosions, the combination was found to very effectively reduce deafness, a common problem among the military and survivors of civilian bombings such as the 1995 Murrah Building bombing.
“If we’re right, this therapy could help not just soldiers dealing with combatrelated hearing loss, but also civilians experiencing age-related hearing loss,” Floyd said.
The drugs have been found safe for human use separately, but the U.S. Food and Drug Administration requires that researchers prove the combination drug is safe and effective, as well.
Kopke said patients with nerve deafness typically say they worked in the oil field, military or on farm equipment.
“If we could help those three groups of people, that would be great,” Kopke said.
The researchers estimate the combination drug will take about five years to get through the trials and secure FDA approval.
“We’re very hopeful and encouraged, and we hope to help prevent deafness in the world,” Kopke said.
Floyd and Kopke’s research has been funded by the U.S. Department of Defense Office of Naval Research.