Now hear this
UF researchers develop new way to test drugs for hearing loss
By Jill Pease
A new way to test anti-hearing-loss drugs in people could help land those medicines on pharmacy shelves sooner. UF researchers have figured out the longstanding problem of how to safely create temporary, reversible hearing loss in order to see how well the drugs work. The findings are described in the November/December 2012 issue of the journal Ear & Hearing.
“There’s a real need for drug solutions to hearing loss,” said lead investigator Colleen Le Prell, Ph.D., an associate professor in the department of speech, language, and hearing sciences at the UF College of Public Health and Health Professions. “Right now the only options for protecting against noise-induced hearing loss are to turn down what you’re listening to, walk away from it or wear ear plugs, and those options may not be practical for everyone, particularly for those in the military who need to be able to hear threats.”
Although prototype drugs have prevented noise-induced hearing loss in laboratory animals, it has been hard to know whether the same protection is possible in humans, largely because researchers lacked an effective method for the needed tests. Those tests are now achievable because of UF efforts. The work brings scientists closer to the development of drugs that could help protect people at risk of hearing damage — from rock concertgoers to factory workers who are routinely exposed to noise as they work.
Le Prell’s model is the first to use controlled music levels to reliably cause low-level, temporary hearing loss in human participants. To induce temporary hearing loss, study participants listened to rock or pop music on a digital music player via headphones for four hours at sound levels ranging from 93 decibels — the noise level of a power lawnmower — to 102 decibels, the noise of a jackhammer. Fifteen minutes after the music stopped, those who listened to the highest music levels had lost just a small amount of hearing — six decibels, on average. Hearing returned to normal within three hours.
Le Prell’s group will use this testing model in two first-of-a-kind clinical trials of therapeutics designed to determine if noise-induced hearing loss can be prevented in humans. The first study uses a dietary supplement called Soundbites, manufactured by Hearing Health Science, a University of Michigan bioscience spinoff company. Soundbites contains the vitamin A precursor beta carotene, vitamins C and E and the mineral magnesium. This antioxidant formula, the patent for which Le Prell shares, has prevented temporary and permanent hearing loss in laboratory animals. In the other ongoing study, participants take a drug called SPI-1005 produced by Sound Pharmaceuticals Inc. The test capsule contains a new molecule called ebselen that mimics a protective inner ear protein.
“We really want to find out what’s going to work and we want to make it possible for strategies that do work to get in the hands of the people who need them,” Le Prell said.