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A Cure For Tinnitus in 2022? OTO-313 Review

Otonomy’s website describes OTO-313 as a drug designed to treat tinnitus, mentioning that “OTO-313 is a sustained-exposure formulation of gacyclidine, a potent and selective NMDA receptor antagonist, in development for the treatment of tinnitus.”

There’s a group of researchers from the company Otonomy (based in San Diego, California) working on a pharmaceutical drug called OTO-313, which is aimed at curing tinnitus. We will discuss the drug’s clinical trials as well as the drug’s effectiveness at treating tinnitus.

Otonomy’s website describes OTO-313 as a drug designed to treat tinnitus, mentioning that “OTO-313 is a sustained-exposure formulation of gacyclidine, a potent and selective NMDA receptor antagonist, in development for the treatment of tinnitus.” A successful phase 1 trial was recently completed, and now the company is advancing OTO-313 into full phase 2 development.

Dr. Thompson explains OTO-313

OTO-313 Initial Clinical Trials

In July 2020, Otonomy reported positive top-line results from phase 1 of OTO-313 in patients with unilateral tinnitus (tinnitus in just one ear) of at least moderate severity. The trial demonstrated a positive clinical response for a single intratympanic injection of OTO-313 (that is, an injection through the eardrum) using the Tinnitus Functional Index, which is a questionnaire that correlates with tinnitus loudness, annoyance, and patient global impression of change measures.

2022 Update: OTO 313 Phase 2 Trials

In early 2022, Otonomy announced that the OTO-313 phase 2 trial was fully enrolled and ahead of schedule. This trial involved a more expanded population of patients with tinnitus in just one ear. In order to make the study more robust, the researchers disallowed patients with severe hearing loss from being included, and they also increased the minimum score of the Tinnitus Functional Index required for entry, thereby expanding the amount of patients who were eligible for entry. The researchers also allowed more individuals to enter based on the timeline of their tinnitus and extended the observation period to assess the durability of the treatment effect. Ultimately, they assembled a sample of 153 patients with persistent unilateral tinnitus of moderate severity.

With this larger sample size, Otonomy have initiated a double-blind test where they will assess the effectiveness of OTO-313 by comparing one group who has been administered the active compound versus a placebo group who hasn’t. If there’s a significant difference, as well as a positive result in the active group, then this will suggest that additional trials should be conducted. Results are expected sometime later this year. 

Oto-313 for Bilateral Tinnitus

When we first posted about OTO-313, many wondered why the initial trials were only focused on unilateral tinnitus. These folks will be happy to find out that in addition to the ongoing phase 2 trial, Otonomy is currently evaluating the safety for higher dosing of OTO-313, as well as dosing in both ears (bilateral dosing). 

That said, as Otonomy’s original theory suggests, OTO-313 hopes to strengthen the auditory nerve fibers in the cochlea (the hearing organ), meaning that different subtypes of tinnitus may not qualify or may not experience noticeable improvement. If phase 2 is successful, Otonomy will then have to meet with the FDA to design the next clinical study, which would then begin in 2023.

OTO-313: A Tinnitus Cure in Development?

So far, the data from the OTO-313 trials have involved a fairly limited sample size. But as the drug gains more traction and undergoes clinical trials, the more the sample size—and thus, the population being studied—will continue to grow.

Of course, these projections are only based on success in the trials. So if data and research emerges saying that the drugs are not successful in an objective double-blind manner, then funding and interest in these trials will diminish. But if the results show promise, then funding and interest will likewise increase.

OTO-313 and similar drugs represent a brand new type of tinnitus treatment, where different drug solutions are put into the cochlea with the ultimate goal of changing the physiology of the inner ear and altering the mechanics and structure of any damaged parts in the hearing system. If it turns out that this is the leading cause of tinnitus, then these kinds of drugs could potentially offer relief, so they are worth monitoring closely for the time being. That said, tinnitus patients should still focus their present efforts on sound therapy and one-on-one counseling with a trained audiologist, as this still represents the best path towards tinnitus habituation.

What To Do Next For Tinnitus

At Treble Health, we know the importance of having a comprehensive approach to tinnitus management. That includes neuroplasticity, sound therapy, and proper medical tests. We put together a consumer guide to help you master tinnitus management so you can improve tinnitus once and for all. Click here to get the free Tinnitus Guide: 2022 Edition

Want to speak with an expert audiologist about your options for tinnitus treatment instead? At the tap of a finger, you can schedule a free Treble Health Tinnitus Consultation today! You’ll be connected with a real audiologist, not a salesperson, and there is no obligation or commitment.

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