OTO-313 is a sustained-exposure formulation of the N-Methyl-D-Aspartate (NMDA) receptor antagonist gacyclidine in development for the treatment of tinnitus.

Tinnitus is most often described as a ringing in the ears but can also sound like roaring, clicking, humming, hissing or buzzing. People with severe tinnitus may have trouble hearing, concentrating, working and sleeping. At this time, there is no cure for tinnitus and there are no FDA-approved drugs for treating this debilitating condition. Historic and emerging clinical data provide support for the evaluation of NMDA receptor antagonists, including gacyclidine, for the treatment of tinnitus.

The goal of our OTO-313 program is to develop a sustained-exposure formulation of gacyclidine that will provide a course of treatment from a single intratympanic (IT) injection. A Phase 1 clinical safety trial has been successfully completed using OTO-311 with no safety concerns observed. We have shifted development to OTO-313, an alternative formulation of gacyclidine that has improved properties compared to OTO-311. We expect to initiate a Phase 1/2 clinical trial for OTO-313 in tinnitus patients in the second quarter of 2019 with results in the first half of 2020.