Aspirin provides clues in search for tinnitus cure

Aspirin is one of the oldest drugs and one of the most useful drugs known to man. It's use as a painkiller is well known, and it has a valuable role to play in preventing heart attack and strokes. There is also increasing evidence that it can provide some protection against some types of cancers.

Less well known is that at high doses, aspirin can cause reversible hearing loss and tinnitus.

Researchers have achieved success in understanding how aspirin can cause hearing loss: the normally rigid structures on sensory cells in the inner ear become softer and 'floppy'.�

How high doses of aspirin, typically about twelve 300 mg tablets per day, could cause tinnitus was still uncertain. The research community have however discovered that before aspirin caused its effects in the ear - it was chemically changed in the blood.

More recent studies carried out by a leading research group at the University of Montpellier in France has provided new clues as to how tinnitus caused by aspirin may occur.�

It was known that aspirin caused changes in the body reducing the production of an important group of molecules that enhanced the perception of pain known as prostaglandins. The production of these pain-enhancing molecules in turn was dependent on a precursor molecule known as arachidonic acid (pronounced ara -ki -do-nic). Arachidonic acid is known to play a vital role in many processes in the body - including having a direct effect on nerve activity.

What the researchers at Montpellier showed is that aspirin at high doses results in increased level in arachidonic acid in the inner ear as it blocked its conversion to prostaglandin. In a series of sophisticated experiments, they found evidence that arachidonic acid appears to affect the activity of the auditory nerve to produce tinnitus. Intriguingly they also showed that another drug, with similar activity to aspirin, also appeared to cause tinnitus.�

They also found pre-treatment with another drug belonging to a group called NMDA blockers, could reduce the tinnitus. NMDA is a term used by neuroscientists to refer to a specific site on nerve fibres that plays a key role in regulating nerve activity. This important work provides new clues to how tinnitus may arise in certain groups of tinnitus sufferers and promises to be invaluable in helping researchers develop new therapies for at least one type of tinnitus.

Action for Tinnitus Research is determined to push the boundaries of research further and keep tinnitus research on the agenda. With your help, we are confident we can find a cure for tinnitus.

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