One of the promising in-ear injections developed to treat acute tinnitus, Keyzilen, has failed another clinical trial. The drug developed by Auris Medical had first failed a clinical trial back in August 2016, not producing statistically significant changes in tinnitus loudness and tinnitus burden compared to a placebo.
Preliminary results of a more recent test completed in January 2018 have been announced and Keyzilen has again failed to produce significant results in the 84 days long trial. The trial was performed primarily in North America, and 343 patients were administered Keyzilen or placebo.
According to Auris Medical, Keyzilen should be able to treat tinnitus caused by an acute injury, such as from exposure to noise, infections, or certain ototoxic drugs. These injuries raise the levels of extra-cellular glutamate, which in turn causes excessive activations of NMDA receptors. This results in damage to sensory cells and can lead to overt activity of auditory nerves, which brains interpret as tinnitus. Keyzilen should address such tinnitus by blocking the NMDA receptors, as they are not known to have an active role in normal hearing.