NRx Pharmaceuticals Inc ( NRXP ) shares are down 23.1% at $2.73 at last check Tuesday.

The stock plummet occurred on the heels of the company’s latest study: the Phase 2b/3 trial of NRX-101 vs. Lurasidone for Suicidal Bipolar Depression.

The investigational drug NRX-101 vs. lurasidone demonstrated a promising, though not yet statistically significant 33% reduction in suicidality together with a 70% reduction (P=.076) reduction in symptoms of akathisia – a side effect of antidepressants that is closely linked to suicide and considered a medical emergency.  

Because of the high-risk nature of these patients, a placebo group could not be employed, and NRX-101, a fixed dose combination of D-cycloserine (DCS) and lurasidone, was compared to lurasidone alone (the standard of care). 

In the company’s previously published STABIL-B trial, NRX-101 was demonstrated to be superior to lurasidone in reducing both depression and suicidality after ketamine while showing a trend toward reducing akathisia. 

In this trial, without prior use of ketamine, NRX-101 and lurasidone were comparable in their effect on depression. 

NRX-101 and lurasidone exhibited comparable antidepressant effects, each reducing depression (the primary endpoint) on the Montgomery Asberg Depression Rating Scale (MADRS) by about 50% from baseline. 

Lurasidone is known to reduce symptoms of depression by approximately 4 points in multiple registration trials compared to placebo.

Analysis of suicidality using the Columbia Suicide Severity Rating Scale (C-SSRS) demonstrated a sustained 33% advantage in remission from suicidality favoring NRX-101. 

This difference was not statistically significant at the phase 2 sample size but met the study’s original promising zone criteria and, if sustained in a registration trial of 300 or more patients, would be powered to yield a statistically significant result. 

The reduction in suicidality is comparable to that demonstrated after ketamine, both in the company’s STABIL-B trial and in an independently conducted trial comparing DCS to placebo after ketamine. 

A meaningful remission in suicidality has not been demonstrated with any prior oral antidepressant drug – indeed, antidepressant drugs carry a Black Box warning of increased suicide risk.

The FDA recently affirmed to the company that the Special Protocol Agreement for this indication remains in place, subject to the company filing a New Drug Approval for ketamine, which is expected by July 2024. 

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