 Study participants will be randomized to SPI-1005 or placebo in this double-blind study to evaluate both safety and efficacy of the investigational treatment. Participants, aged 18-75 years, with probable or definite Menieres disease will undergo baseline testing to assess severity of sensorineural hearing loss, tinnitus and vertigo. During the study, and 28 days after completion of treatment, participants will be evaluated for safety adverse events, physical examinations, vital signs and clinical laboratory testing CBC,serum chemistry. Trough plasma levels of ebselen and its major metabolite will be determined using liquid chromatography-mass spectrometry LCMS at specified visits. Additionally, plasma will be analyzed for selenium at the corresponding visits. The effect of SPI-1005 on hearing and balance will be evaluated. Tinnitus TFI and vertigo VSS will be evaluated at baseline, during and study treatment. 