Acute inner ear hearing loss is the sudden onset of hearing loss, usually in one ear, without any known cause. Those affected experience hearing loss and are only able to hear sounds or conversations in a muffled way. Hearing can often recover slightly or completely in the days and weeks afterwards. However, there remains the possibility of ongoing damage; the more severe the initial hearing loss, the greater the risk of permanent hearing damage. Besides loss of hearing, other symptoms frequently occur, in particular ringing in the ear and/or dizziness. These symptoms may disappear after just a short time but in other cases can persist for a long time. Acute hearing loss can permanently destroy some of the hair cells (that govern the sense of hearing) and/or hearing nerve in the inner ear. Cells that are affected by this process die off within a few hours to several days. The result is permanent hearing loss, for which there is still no successful method of treatment.
The drug AM-111 has been developed to protect the hearing cells and nerve following sudden inner ear hearing loss. In animal experiments, AM-111 prevented/reduced death of hair cells (in the inner ear) and thus permanent hearing loss. In addition, AM-111 was found to reduce inflammation in the inner ear, which could also improve restoration of normal hearing. For AM-111 to be effective, the drug should be administered as soon as possible after the occurrence of sudden hearing loss, in order to protect the cells at risk of cell death. The protected cells are thereby able to recover in the days and weeks following hearing loss and to continue carrying out their function. This is the third study in which the study drug is being used in humans suffering from sudden deafness. In the previous studies, a total of 221 patients received AM-111 or placebo. The study drug showed effectiveness in patients with severe to profound hearing loss and was found to be very well tolerated.