Gabapentin was no more effective than placebo in relieving tinnitus

The study shows that Gabapentin was no more effective than placebo in relieving tinnitus, according to the results of an 8-week randomized trial issue of the Archives of Otolaryngology–Head & Neck Surgery.

"The available evidence, based on clinical observation and electrophysiologic studies during the past decade, suggests that tinnitus is associated with disturbances in spontaneous neural activity in the auditory system (central-origin hypothesis)," write Jay F. Piccirillo, MD, from Washington University School of Medicine in St. Louis, Missouri, and colleagues. "The goal of this study was to assess the role of gabapentin in the treatment of tinnitus. In particular, we wanted to investigate whether the findings of therapeutic benefit with gabapentin reported in some of the published literature could be replicated in a randomized double-blind trial."

In this study, 135 patients, 18 to 70 years of age (mean age, 57.0 ± 8.2 years) with severe idiopathic subjective tinnitus of 6 months' or more duration, were randomized to receive gabapentin, at a maintenance dosage of 900 to 3600 mg/day for 8 weeks, or lactose placebo. Patients with treatable otologic disorder causing tinnitus, organic mental disorder, impaired renal function, or previous use of gabapentin were excluded. Participants discontinued all tricyclic antidepressants 30 days before study entry and did not use any other treatment of tinnitus during the study.

The main outcome measure was change in Tinnitus Handicap Inventory (THI) score (scored from 0 - 100) from baseline to study termination at 8 weeks. Secondary outcomes were American Tinnitus Association data collection forms and questionnaires, 18-item Brief Symptom Inventory, Beck Depression Inventory, and the Patient Global Impression of Change questionnaire.

Of 135 subjects who enrolled, 115 completed the study. Most withdrew for lack of efficacy; of the 9 who withdrew because of adverse effects, 3 reported nausea, 2 weight gain, 2 sleep disturbance, and 2 reported dizziness, all of which stopped when study medication was discontinued.

From baseline to week 8, overall change in THI for the entire cohort was 11.2 (11.3 in the gabapentin group and 11.0 in the placebo group; difference, 0.03; 95% confidence interval, -5.5 to 6.2; P = .91). Change of 20 points or more on THI was achieved by 22 subjects (37%) in the gabapentin group scores vs 18 (32%) in the placebo group (P = .56).

Among subjects with normal hearing, there was a significant change in THI score at weeks 0, 4, and 8 between the gabapentin and placebo groups. Those who received gabapentin had a 21.40-point change in THI score from weeks 0 to 8 vs 1.75-point change in those who received placebo (P = .005). However, this apparent response to gabapentin was not supported by other outcome measures such as the global rating of response or satisfaction with care.

The gabapentin and placebo groups did not differ in their overall degree of life disturbance because of tinnitus, their overall impression of change in tinnitus, and whether they would recommend the product they received to a friend.

"Despite basic scientific evidence, a case report of success in treatment of tinnitus with gabapentin, and clinical similarities between tinnitus and neuropathic pain, we did not find that gabapentin was clinically efficacious for the treatment of tinnitus," the authors conclude. "To date, the US Food and Drug Administration has not approved any drug for the treatment of tinnitus. Future clinical trials should continue to explore the effect of other centrally acting drugs."

Dr. Piccirillo has disclosed serving as a member of the advisory board for Merck Santé's Acamprosate in Tinnitus project. The National Institute on Deafness and Other Communication Disorders supported this study.