Tinnitus is a frequent disorder and very difficult to treat. Both animal studies and clinical observations suggest that dopaminergic substances might have potential for the treatment of tinnitus. Here, we investigated the dopamine agonist piribedil for the treatment of chronic tinnitus. In all participants, we performed audiometry, electrocochleography (ECoG), and otoacoustic emissions before treatment began.
To assess the efficacy and safety of the dopaminergic drug piribedil for the treatment of tinnitus and to evaluate whether ECoG and acoustic otoemissions might be useful for predicting treatment response.
Prospective randomized double-blind crossover study.
One hundred patients with tinnitus were randomized into a double-blind, placebo-controlled, prospective crossover study. All patients underwent distortion product acoustic otoemissions with and without contralateral suppression and ECoG. Patients received 50 mg piribedil and placebo for 90 days each, separated by a 30-day washout period. Treatment effects were assessed by using the Tinnitus Handicap Inventory and a visual analog scale. Fifty-six patients completed the trial.
There was no significant improvement of Tinnitus Handicap Inventory and visual analog scale score after piribedil treatment as compared with placebo. However, results were characterized by high interindividual variability. Post hoc analysis of piribedil effects revealed that piribedil treatment responders differed from nonresponders by the occurrence of a double peak in the ECoG. In addition, normal distortion product acoustic otoemission suppression patterns indicated better treatment response with piribedil. The incidence of side effects during piribedil treatment was 23.3%, leading to interruption of treatment in all cases.
Piribedil is not superior to placebo in the treatment of tinnitus. Piribedil treatment responders differed from nonresponders by specific findings in the ECoG and in the distortion product acoustic otoacoustic emissions, suggesting a beneficial effect of piribedil in an electrophysiologically characterized tinnitus subgroup.
The study has been registered in Clinical Trials.gov under the number NCT00591994.
*OTOSUL, Otorrinolaringologia Sul-Fluminense, Volta Redonda, Rio de Janeiro, Brazil; †Department of Psychiatry, University of Regensburg, Regensburg, Germany; and ‡Valença Medical School, Valença, Rio de Janeiro, Brazil
Address correspondence and reprint requests to Andréia Aparecida de Azevedo, M.D., Rua 40, n 20, Salas 216 a 218, Vila Santa Cecília, Volta Redonda, Rio de Janeiro CEP 27255-650, Brazil; E-mail: email@example.com
This research was supported by a grant from the Tinnitus Research Initiative. The study has been registered in Clinical Trials.gov (no. NCT00591994).