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.

The authors of "Tinnitus Treatment With Acamprosate: A Double Blind Study," are Andréia Aparecida de Azevedo MD, and Ricardo Rodrigues Figueiredo MD, both affiliated with Otolaryngology Sul Fluminense, São Camilo Hospital, Volta Redonda, R.J., Brazil. Their findings are to be presented at the 109th Annual Meeting & OTO EXPO of the American Academy of Otolaryngology—Head and Neck Surgery Foundation, being held September 25-28, 2005, at the Los Angeles Convention Center, Los Angeles, CA.

Methodology: Fifty patients with tinnitus complains were selected by OTOSUL, in São Camilo Hospital, in Volta Redonda City, state of Rio De Janeiro, Brazil. The patients' tinnitus could be linked to sensorineural hearing loss. Patients were classified by age, gender, unilateral or bilateral tinnitus, interrupted or uninterrupted tinnitus, tinnitus feature, time, simultaneous symptoms, probable etiology, previous therapeutics and score from 01 to 10, referred by the patients to their discomfort. Each patient was asked to provide a score that quantified his or her tinnitus from 01 to 10.

The patients were classified in two groups of 25 patients each. A prescription of acamprosate (333 mg) was given to one group three times a day, and a placebo, three times a day, to the other group. The patients were analyzed 30, 60, and 90 days after they started taking the medicine and any change in their tinnitus score and side effects was recorded.

Results: The patients' age was between 35 and 82 (average: 60; .58 percent of patients were male, 42 percent, female. Features of the disorder reported were: creak, 62 percent; whistle, 46 percent; and more than one kind of sound, 16 percent. The duration time of the disorder ranged from one to 420 months with 9.76 percent having the disorder less than one year; 53.65 percent had intermediate tinnitus (one to seven years); and 36.59 percent had the condition longer than seven years. The researchers found 58 percent of patients had bilateral tinnitus, 72 percent had uninterrupted tinnitus and 64 percent had associated symptoms, which included hearing loss, dizziness, ear pressure, and hyperacusia (abnormal hearing sensitivity). Slightly more than half of the percent of the patients had used drugs to treat tinnitus before.

After 90 days, nearly half of the group taking acamprosate stated their tinnitus had declined by half; significantly higher than in the placebo group. Additionally, those in the acamprosate group increase in tinnitus severity. Three patients did not register improvement; nine patients had an improvement less than 50 percent, and 11 patients (47.83 percent) referred an improvement higher than 50 percent. Three patients had the tinnitus disappearance.

Conclusions: The authors suggest that because acamprosate can offer a satisfactory therapeutic perspective to tinnitus because the drug has a dual mechanism action, which decreases the Glu transmission (afferent-excitatory) and increases GABA (efferent-inhibitory), with excellent tolerability.

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. There was no significant difference in tinnitus improvement with age, gender, etiology, time, and type of tinnitus, as well as the hearing loss level and the audiogram. Conclusion: The study results convince the authors that acamprosate, a drug approved by FDA to treat alcohol dependence, with a dual mechanism of action in Auditory Pathways and Central Nervous System is a good alternative to our therapeutic arsenal to treat tinnitus.