Prolonging Residual Inhibition with Eglumegad

Might be of interest.

Here is the link:

1pAB6 – Long-lasting suppression of spontaneous firing in inferior colliculus neurons: implication to the residual inhibition of tinnitus

Of significance is the author's comments regarding the research already undertaken on residual inhibition and its ability to help science identify a group of drugs that can alter the suppression response, as well as the 'spontaneous firing of the auditory neurons responsible for tinnitus. These drugs will be further investigated in our future research to develop effective tinnitus treatments.'

I emailed the author, Prof. Galazyuk.

This is his response with relation to pharmaceutical developments for tinnitus.

The name of the drug is Eglumegad, which is a group 11 mGluR agonist.

 

Update 4 years later:

I touched base with Prof. Galazyuk recently.

He's submitting a grant proposal to the NIH to further his clinical trials.

Preliminary trials in animals showed relief from tinnitus for two hours using this compound (2016).

 

I just read parts of Galazyuk's article. His proposed model of tinnitus certainly makes sense: an increased in spontaneous hyperactivity above a certain threshold is shifted from cochlea to central nervous system; thus we are stuck with tinnitus when the cochlea recovers. This is consistent with studies where the cochlear nerve is severed but tinnitus is not resolved nor improved. It's also consistent where some people with hearing loss do not have tinnitus because that hyperactivity has not shifted to the CNS or the hyperactivity has not reached above a certain threshold.

I wonder what Dr. Will Sedley's predictive tinnitus model thinks about this.

So the question is: how likely will healing the cochlea (regenerating damaged hair cells) resolve/improve tinnitus symptoms?

 

Further to this study, when asked about financing, here is Prof. Galazyuk's response:

 

Wait, they did Phase 1 already? Or is this Phase 1/2?

 

I think he's hoping to move to Phase 2 because he said earlier that they've already tested its efficacy in animals.

 

Phase 1 is safety. Normally, for issues like tinnitus, it becomes a Phase 1/2 trial for safety and efficacy. To move to just Phase 2 on humans without a safety is unlikely. He probably means Phase 1/2.

 

Then why do cochlear implants resolve or reduce tinnitus in many, even in a sound proofed room? And some cochlear nerve ablations do resolve tinnitus. So "stuck in the brain" seems nonsense.

Also an update from NEOMED Hearing research today:

Been a long time though...

 

Update:

I have received an email response from Alex Galazyuk regarding Eglumegad.

• Eglumegad activates group 2 metabotropic glutamate receptors - suppresses hyperactive neuronal activity.
• The director of a USA based pharmaceutical company (who suffers with bothersome tinnitus himself) has informed Alex in December 2023, that Eglumegad will hopefully be moving to a clinical trial (as Eli Lilly have expressed interest in leasing their drug for a clinical trial).
• Discussions during an internal meeting will occur January - February 2024.

I'll update when I hear anything further.

 

I looked at Eglumegad a few days ago by coincidence.

To summarise:

This thread started 8 years ago now and it is frustrating that this is not, at the very least, in human clinical trials.

• It seems this treatment possibility was born out of research into the inferior colliculus.
• It found hyperactivity in this area of the brain and it has been postulated to occur because of increased activity in the cochlear nucleus. The inferior colliculus is the next part of the brain where sound is processed after it passes through the cochlear nucleus.
• The drug is an agonist of the Glut 2 neurotransmitter.
• It has been found to decrease tinnitus in animal models, albeit, only for 2 hours.

 

Even if this only undid the noise for 2 hours at a time, it'd be great to have a few hours of quiet each day.

 

Maybe after years of R & D, it's time to invite Prof. Galazyuk onto the Tinnitus Talk Podcast, @Hazel, @Markku, and get him to summarise his findings, animal study results and where he is in relation to starting human clinical trials?

 

I'm a layman in this so it doesn't make sense to me that Eglumegad is a glutamate agonist. I thought that tinnitus was the result of overactive cells that needed to be calmed down. So I would expect a glutamate antagonist to work, not an agonist. Does anyone know?

 

Like not literally now.

Me too!

 

Eglumegad is not a glutamate agonist, it is an agonist of the metabotropic glutamate receptor 2 (mGluR2). mGluR2 is a so called autoreceptor located at the presynaptic terminal. When glutamate, or an agonist like Eglumegad, binds to it, it decreases vesicular glutamate release. In that way it has a similar effect as Keppra, which reduces vesicle release through SV2A binding and blocking presynaptic calcium channels.

Interestingly enough, "previous research indicates that NAC increases extracellular glutamate, which is then thought to decrease neuronal glutamate release via activation of presynaptic mGluR2/3 receptors."

Unfortunately mGluR2 is not expressed in the inner ear.