A Randomized Trial of Intratympanic Drug Delivery: Evaluating the Efficacy and Safety of Dexamethasone-Loaded Exosomes Versus Standard Therapy in Acute Sensorineural Hearing Loss. (EXO-DEX-SNHL)

SSNHL is defined as a rapid-onset hearing loss of ≥30 dB over at least three contiguous frequencies within a 72-hour period, with an incidence of 5-20 per 100,000 persons annually (1).

The idiopathic nature of most cases suggests multifactorial pathogenesis, including viral infections, autoimmune responses, and vascular ischemia, culminating in cochlear inflammation and oxidative stress (2).

The standard of care involves systemic corticosteroids, with salvage IT corticosteroid injections for non-responders. However, the blood-labyrinth barrier and the round window membrane pose significant anatomical and physiological barriers to effective drug delivery, resulting in sub-therapeutic inner ear drug levels and potential systemic toxicity (3, 4).

Exosomes (30-150 nm) are natural vesicles secreted by most cell types, playing crucial roles in intercellular communication via transport of proteins, lipids, and nucleic acids (5). As drug delivery vehicles, they offer intrinsic biocompatibility, low immunogenicity, and an innate ability to cross biological barriers.

Preclinical studies demonstrate that exosomes can be loaded with therapeutic agents, such as dexamethasone, and targeted to specific tissues, enhancing drug bioavailability and retention while minimizing off-target effects (6, 7).

The investigators hypothesize that IT administration of exosomes loaded with dexamethasone will result in superior therapeutic outcomes compared to conventional IT dexamethasone by improving perilymphatic pharmacokinetics, prolonging cochlear retention, and providing synergistic anti-inflammatory and cytoprotective effects via exosome-mediated signaling.