Sudden sensorineural hearing loss (SSNHL) is an otologic emergency characterized by rapid onset of hearing loss, typically unilateral, occurring over less than 72 hours. The annual incidence is estimated to range from 5 to 30 per 100,000 individuals, with the highest prevalence among adults aged 40-60. The etiology of SSNHL remains idiopathic in most cases, though proposed mechanisms include viral infections, autoimmune responses, vascular compromise, or membrane rupture in the inner ear. In addition to hearing loss, patients commonly report tinnitus, ear fullness, and vertigo, which may significantly affect quality of life.
Standard treatment modalities for SSNHL include systemic corticosteroids and, in moderate to severe cases, hyperbaric oxygen therapy. However, current literature indicates that only approximately 60% of patients achieve significant improvement, leaving a substantial proportion with residual deficits. There remains an unmet need for adjunctive therapies that are both effective and safe.
The investigational product in this study is 'Inner ear support' oral capsule, a commercially available dietary supplement composed of FB-1603 (a cold water extract of Arthrospira maxima), gamma-aminobutyric acid (GABA), gamma-oryzanol, and sesamin. Among these, FB-1603 contains biologically active compounds such as C-phycocyanin, a pigment-protein complex that has demonstrated antioxidant, anti-inflammatory, and neuroprotective properties in preclinical studies.
In vitro studies show that FB-1603 significantly reduces LPS-induced cytotoxicity and suppresses the expression of pro-inflammatory markers such as iNOS, COX-2, TNF-α, and IL-6 in BV-2 microglial cells. Animal studies using salicylate-induced tinnitus models in mice have demonstrated that dietary supplementation with FB-1603 or C-phycocyanin attenuates the expression of auditory-related inflammatory genes (e.g., TNF-α, IL-1β, COX-2, NR2B) in the cochlea and inferior colliculus.
Additional preclinical evidence suggests that FB-1603 modulates the expression of ion transporters such as KCC2 and NKCC1, potentially restoring auditory neural excitability. In senescence-accelerated mouse models, FB-1603 was found to enhance antioxidant enzyme expression (SOD, catalase, GPx), suggesting a protective role against age-related hearing decline. These findings form the basis for evaluating FB-1603 as a candidate therapeutic agent for sensorineural hearing dysfunction.
This randomized, open-label, single-center clinical trial aims to evaluate the efficacy and safety of 'Inner ear support' oral capsule in patients with SSNHL. A total of 80 patients will be enrolled and randomly assigned to two groups: both will receive standard treatment with systemic corticosteroids (with or without hyperbaric oxygen), but only the experimental group will receive 'Inner ear support' 600 mg daily (administered as two 300 mg capsules per day) for 28 days.
The primary endpoint is the change in pure tone audiometry (PTA) thresholds from baseline at Days 28, 84, and 168. Secondary endpoints include the incidence of adverse events, changes in clinical laboratory parameters (hematology, biochemistry, ECG), and patient-reported outcomes such as the Tinnitus Functional Index (TFI) and Dizziness Handicap Index (DHI).
All participants will undergo safety monitoring, and any adverse events will be recorded and evaluated. The study hypothesis is that 'Inner ear support', when added to standard treatment, will improve auditory recovery and reduce the severity of associated symptoms such as tinnitus and dizziness, without introducing significant safety risks.
This investigation will provide essential clinical data regarding the utility of a plant-derived, nutraceutical formulation as a novel adjunctive approach to managing SSNHL. If successful, 'Inner ear support' could offer a safe, accessible option to improve outcomes for patients affected by this disabling condition.
Study Design and Visit Schedule
This is a randomized, open-label, single-center clinical study. A total of 80 participants diagnosed with SSNHL will be randomly assigned in a 1:1 ratio to either the experimental group or the control group. Both groups will receive standard-of-care treatment including systemic corticosteroids, and, if clinically indicated, hyperbaric oxygen therapy. The experimental group will additionally receive 'Inner ear support' oral capsule at a dose of 300 mg twice daily for 28 days.
Participants will be evaluated at baseline (Day 0) and subsequently on Days 28, 84, and 168. Each visit will include:
* Pure tone audiometry (PTA)
* Laboratory tests (hematology, biochemistry)
* Electrocardiogram (ECG)
* Tinnitus Functional Index (TFI)
* Dizziness Handicap Index (DHI)
* Adverse event and safety assessments
Compliance and concomitant medication usage will also be recorded. Audiologic tests will follow standard frequencies (e.g., 0.5, 1, 2, and 4 kHz), and hearing threshold changes will be calculated as the mean difference compared to baseline.
Pharmacological Mechanism and Molecular Action of 'Inner ear support'
The primary active ingredient in 'Inner ear support' is FB-1603, a cold water extract of Arthrospira maxima, rich in the pigment C-phycocyanin (C-PC). C-PC exerts antioxidant and anti-inflammatory effects via several mechanisms:
* Suppression of oxidative stress: FB-1603 upregulates antioxidant enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase, reducing reactive oxygen species (ROS) in cochlear and brainstem tissues.
* Neuroprotection: C-PC inhibits pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) and enzymes like iNOS and COX-2, preserving neural integrity under oxidative or inflammatory stress.
* Modulation of ion transport: FB-1603 downregulates aberrant expression of potassium-chloride co-transporter KCC2, implicated in auditory hypersensitivity and tinnitus, restoring synaptic excitability.
These actions are supported by in vivo studies in mouse models of salicylate-induced tinnitus and age-related hearing loss, where FB-1603 administration reduced auditory threshold shifts, inflammation-related gene expression, and tinnitus behavioral scores.
Statistical Analysis
This study will primarily employ:
* Paired and independent t-tests to assess changes in pure tone audiometry (PTA) between and within groups at multiple timepoints (Days 28, 84, 168).
* Chi-square tests for categorical data such as the proportion of patients with clinically significant improvement in hearing or symptom scores (TFI, DHI).
* All p-values will be two-sided, with a significance level set at α = 0.05.
Descriptive statistics (mean, standard deviation, range) will be presented for all quantitative outcomes. Safety analysis will summarize adverse events by type, severity, and relationship to the investigational product. Missing data will be handled using intention-to-treat principles; sensitivity analyses may be performed to evaluate robustness.
