Drug may reverse deafness

Auckland University researchers have shown a potent new drug may reverse hearing loss caused by prolonged exposure to loud noise at work, at rock concerts, or listening to MP3 players.

Their work could pave the way for therapies to restore hearing loss without the need for cochlear surgery.

The researchers began work several years ago injecting a chemical agent called "ADAC" into rats whose hearing had been damaged by noise.

They found a five-day treatment of daily injections, starting six hours after exposure to noise, were most effective. Single treatments were less effective but also resulted in some hearing recovery.

The chemical targeted molecules, known as adenosine receptors, found in the inner ear's hair cells. The drug is thought to work by increasing the ability of sensory hair cells to break down damaging waste products, which build up during noise exposure.

The body produces acidic molecules called free radicals which can damage cells - a process scientists see as sometimes related to ageing processes.

But they also think that when a concertgoer is bombarded with noise from over-amped speakers, their ear mechanism is placed under stress which, in turn, causes the production of free radicals that slowly but surely lessen the ability to hear.

The Auckland Medical Research Foundation said lead researcher Srdjan Vlajkovic had paved the way for effective non-surgical therapies to restore hearing loss after noise-induced injury.

Dr Vlajkovic's work was published yesterday in the journal, Purinergic Signalling.

His team found both cochlear injury and hearing loss in rats was substantially restored by the drug.

"We now hope to test its effectiveness in humans and are currently seeking industry partners to move this to clinical trials," Dr Vlajkovic said.

The discovery has been published just as the Government was changing the rules on ACC's coverage of hearing loss caused by working in a noisy environment.

Until now, ACC has covered all costs for hearing aids and associated audiology fees.

As of this month, the person will have to have at least 6 per cent hearing loss to qualify. And by the end of the year, a person's age will be taken into account.

As the person gets older, more of the hearing loss will be attributed to age and therefore not covered by ACC, which pays out about $80 million a year in audiology costs.

- NZPA