NRx Pharmaceuticals, Inc. announced that the U.S. Food and Drug Administration (FDA) denied the Breakthrough Therapy designation (BTD) request for ZYESAMI® (aviptadil) and emphasized its focus on the company's NRX-101 BTD compound for Bipolar Depression associated with Suicidality. The request for BTD was submitted based on the positive finding of a post-hoc subgroup analysis of patients who in addition to Aviptadil or placebo were also treated with Remdesivir and whose respiratory failure due to Critical COVID-19 continued to progress.