New Weapon Against Hearing Loss? Marines Participating in Clinical Trial to Prevent Hearing Loss Features
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Features  |   February 01, 2004
New Weapon Against Hearing Loss?
Author Notes
  • Susan Boswell, an assistant managing editor of The ASHA Leader, can be reached at sboswell@asha.org.
    Susan Boswell, an assistant managing editor of The ASHA Leader, can be reached at sboswell@asha.org.×
Article Information
Hearing Disorders / Features
Features   |   February 01, 2004
New Weapon Against Hearing Loss?
The ASHA Leader, February 2004, Vol. 9, 1-21. doi:10.1044/leader.FTR1.09032004.1
The ASHA Leader, February 2004, Vol. 9, 1-21. doi:10.1044/leader.FTR1.09032004.1
The nation’s first clinical trial is underway at a California military base to test an antioxidant compound that may prevent noise-induced hearing loss.
As part of the first controlled trial that began Feb. 1, 500 recruits at the Marine Corps Recruit Depot in San Diego are testing the effects of “The Hearing Pill™.” Developed by the U.S. Navy and marketed as a dietary supplement by American BioHealth Group, a San Diego pharmaceutical firm, the pill is being sold to consumers without a prescription.
The pill may prove to be the military’s best weapon against noise-induced hearing loss, which is one of the most prevalent occupational hazards facing members of the armed services and costs the military more than $200 million in compensation annually.
“About 10% of military personnel will suffer noise-induced hearing loss-even though they use hearing protection,” said Brenda Lonsbury-Martin, ASHA’s director of science and research.
The Marine recruits have been randomized into groups under the direction of Army Col. Richard Kopke, a military otolaryngology researcher and co-director of the Department of Defense Spatial Orientation Center at the San Diego Naval Medical Center.
The recruits’ hearing will be tested prior to training and at the end of the study. The results of participants’ final test will be compared to their pre-training hearing levels. Testing will consist of pure-tone audiograms, including an extended audiogram from 8–16 kHz to examine the susceptibility of the basal cochlear region to noise damage, and otoacoustic emissions testing.
“This is the first serious effort based upon scientifically based evidence to test the feasibility of this compound,” said Lonsbury-Martin, who serves as a scientific consultant to Kopke’s study, noting that the results will be published. “It will be sensational news if it works.”
The active ingredient in The Hearing Pill is N-acetyl cysteine (NAC), an amino acid that helps synthesize antioxidants. A series of studies using animal models published in the peer-reviewed literature has demonstrated the protection of antioxidants against noise-induced damage to cochlear hair cells, Lonsbury-Martin noted. Researchers at the University of Michigan blasted guinea pigs with noise at 115 dB for five hours, resulting in a hearing loss of up to 50 dB. The guinea pigs that had been given NAC prior to the noise exposure, however, showed minimal hearing loss.
“Our study with NAC on noise-induced hearing loss showed that this antioxidant will protect against the damage caused to guinea pigs by excessive noise,” said Jochen Schacht, professor and director of the Kresge Hearing Research Institute at the University of Michigan.
“We also have shown-and the literature is in agreement on this fact-that protection is most efficient when the therapeutic agent is given before the noise exposure. It is not known whether a ‘window of rescue’ exists after noise damage. Prevention is clearly indicated.”
Regulatory Status
The U.S. Food and Drug Administration (FDA) has approved the use of NAC for indications unrelated to otoprotection. One approved use is to protect against renal damage from an overdose of acetaminophen (Tylenol). The antioxidant compound is available through health food stores and Web sites and purports to support the immune system, increase muscle strength, synthesize protein, metabolize fat, and prevent kidney damage from certain coronary procedures.
Labeled as a dietary supplement, The Hearing Pill does not need prior FDA approval, according to an agency spokesperson. Connie Bulawka, a consumer safety officer with the FDA’s Office of Compliance of the Center for Drug Evaluation and Research, said, “The Hearing Pill is under review right now,” but declined to elaborate.
David Karlman, chair and chief executive officer of American BioHealth, noted, “A significant amount of laboratory data suggests that it’s effective. If we obtain clinical evidence of its effectiveness, we will label the product as being ‘clinically proven.’”
Added Lonsbury-Martin, “As a consumer, FDA approval gives you the safety factor, but the drug’s cost increases as companies seek to recoup their investment. Over-the-counter (OTC) drugs are cheap and competitive,” she said. “It may be positive for consumers because they may be more willing to protect themselves.”
Besides presbycusis, noise exposure in our industrial society is one of the biggest causes of hearing loss, Lonsbury-Martin said. “Studies have shown that in non-industrial societies, people have pristine hearing thresholds as octogenarians. An OTC drug may promote better communication later in life.”
Karlman said that American BioHealth Group is “pleased and surprised at the volume of sales.” About 12% of all sales are from abroad in Malaysia, Korea, the United Kingdom, and the Netherlands, he noted, adding that “a major national retail chain is interested in carrying our product.”
For more information about other otoprotective compounds in development, watch for an in-depth article in a future issue of The ASHA Leader.
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February 2004
Volume 9, Issue 3