The primary objective of this study is to determine the safety and efficacy of SPI-1005 treatment in CF patients with active pulmonary exacerbation that are receiving an IV course of tobramycin, determined by comparing hearing assessments, spirometry, Pharmacokinetic (PK), Physical Exam, Adverse Events (AEs) and Labs baseline to post-treatment.

The secondary objectives of this study are to determine Pharmacogenomics and Pharmacodynamics of SPI-1005.

Randomized, double-blind, placebo-controlled study to evaluate the safety, and efficacy of SPI-1005 in Cystic Fibrosis patients with Acute Pulmonary Exacerbation receiving intravenous tobramycin at risk for ototoxicity. All patients will undergo baseline testing and have their severity of lung function, sensorineural hearing loss, tinnitus and vertigo determined before the start of SPI-1005 treatment. SPI-1005 treatment will start within first two days of IV tobramycin treatment and be administered concomitantly. At the end of the 21-day course of SPI-1005 and 28 days following the cessation of SPI-1005, patients will have their hearing loss, tinnitus and vertigo reassessed. Assessments may also include additional audiometric and pulmonary testing, and additional follow-up testing.

Inclusion Criteria:

• Cystic fibrosis patients about to receive IV tobramycin for acute pulmonary exacerbation.
• Voluntarily consent to participate in the study.
• Females of childbearing potential should be using and committed to continue using one of the following acceptable birth control methods:
• Sexual abstinence (inactivity) for 14 days prior to screening through study completion; or IUD in place for at least 3 months prior to study through study completion; or Barrier method (condom or diaphragm) with spermicide for at least 14 days prior to screening through study completion; or Stable hormonal contraceptive for at least 3 months prior to study through study completion.
• Ability to perform all behavioral tests as indicated.

Exclusion Criteria:

• Current use or within 60 days prior to study enrollment the following IV ototoxic medications: aminoglycoside antibiotics (gentamicin, tobramycin, amikacin, streptomycin); platinum-containing chemotherapies (cisplatin, carboplatin, oxaliplatin); or loop diuretic (furosemide).
• History of idiopathic sensorineural hearing loss, otosclerosis, or vestibular schwannoma.
• History of middle ear or inner ear surgery.
• Current conductive hearing loss or middle ear effusion.
• Significant cardiovascular, hepatic, renal, hematologic, endocrine, immunologic, or psychiatric disease.
• History of hypersensitivity or idiosyncratic reaction to compounds related to ebselen.
• Participation in another investigational drug or device study within 30 days prior to study enrollment.
• Female patients who are pregnant or breastfeeding.

Adverse event data were collected from study consent until 4 weeks post-tobramycin, i.e., approximately 5-7 weeks.