Thursday, September 29, 2005

Drug Approved to Help Alcoholism Also Effective Against Tinnitus

This is the kind of thing that I love about pharmacology.  Acamprosate (Campral ®) was released earlier this year as a drug that reduces craving in persons with alcoholism.  My earlier post reviews the pharmacology of the substance.   Now comes a study that shows possible benefit for sufferers of tinnitus.  
Drug Approved to Help Alcoholism Also Effective Against Tinnitus

Newswise — On July 29, 2004, The U.S. Food and Drug Administration has approved the drug acamprosate, marketed under the brand name Campral®, for treating alcohol dependent individuals seeking to continue to remain alcohol-free after they have stopped drinking. Two Brazilian researchers believe that the drug is also effective in treating tinnitus, a disorder that affects 12 million Americans with noises in their ears.

Acamprosate (calcium acetylhomotaurine), an analog of homotaurine, and a GABA-ergic agonist, stimulates inhibitory GABA-ergic neurotransmission in the brain and antagonizes the effects of certain excitatory amino acids, such as Glutamate. Since acamprosate activates postsynaptic GABA B receptors (but not GABA A receptors) in vitro and decreases electrical excitability, but does not change membrane potential, the researchers set out to evaluate the acamprosate efficacy and safety as a treatment for sensorineural tinnitus, with a double blind study.
At first glance, tinnitus does not appear to be a serious problem.  It is the sort of think that does not attract a lot of research effort; few centers will get a multimillion dollar grant to study it.  Usually, it is a minor nuisance, but some people have it so bad that they are disabled by it.  

Certainly, there is no obvious connection between alcoholism and tinnitus.  Likewise, there is no obvious reason to think that a drug that would help with one condition would help with the other.  Granted, the results were not spectacular:
In this study, those taking the drug registered a significant overall improvement rate (86.9 percent) and 47.8 percent of the cases reporting improvement better than 50 percent. Additionally, a decrease in was noted in the tinnitus discomfort rate when compared from the initial rate in the period of 90 days.
Only half the patients had an improvement of greater than 50%.  However, for many patients, even a modest improvement would be extremely helpful.  Especially since there really aren't a lot of alternatives.

Although alcoholism and tinnitus have nothing to do with each other, in terms of symptoms, or ultimate cause, the pathophysiology of the two conditions appear to share a common pathway.  Understanding of that pathway is what led to this discovery.  This study shows how a thorough understanding of the basic pathophysiology of a problem can lead to ideas for a solution.  It is a good example of why preclinical research is worthwhile.  It also illustrates how efforts to direct funding mainly to solving practical problems can be a misguided strategy.