GRX-917 is a proprietary (patent-protected until 2036), improved version of Etifoxine, an anxiety drug first approved in France 39 years ago. GRX-917 is a deuterated version of Etifoxine (specific hydrogen atoms were replaced by isotopic deuterium atoms). Like the vast majority of deuterated drug analogs, GRX-917 retains the same mechanism of action and pharmacological properties as the original non-deuterated form, because the biological properties are identical.

Clinically, GRX-917’s speed of onset, efficacy and side effects profile will be identical to the original drug. However, the pharmacokinetic profile is significantly improved as a result of reduced metabolism due to deuterium stabilization. This is expected to lead to lower and/or less frequent dosing. Critically, GRX-917 also has an identical metabolite profile but with reduced overall amounts of metabolites. As such, GRX-917 is expected to retain or potentially improve upon Etifoxine’s post-marketing good safety profile.

“Equivalent efficacy to benzodiazepines like Xanax, without the side effects.”

On-Market Drug

Etifoxine (Stresam™) is an anxiety medication sold in France since 1979, and more than 25 other countries around the world. Clinically, it has shown rate of onset and efficacy equivalent to Xanax and Ativan, two of the world’s top selling benzodiazepines, but without the sedation, cognitive impairment, withdrawal effects or abuse. To view a history of the drug, click here.

The unique combination of the drug’s selective effects at GABA channels, coupled with the ability to substantially increase the levels of important, natural neurosteroids (like allopregnanolone), give the drug an unrivaled anxiolytic profile of fast onset without the dangers or typical side-effects of benzodiazepines. Upregulation of neuroactive steroids by etifoxine may also account for its recently discovered neurotrophic, neuroprotective and anti-inflammatory properties. The drug has demonstrated efficacy in a large number of animal models of neuropathic and inflammatory pain, multiple sclerosis, epilepsy, Alzheimer’s disease, stroke, traumatic brain injury, nerve/spinal cord injury and retinal/macular degeneration.


In 2012, the French National Agency for the Safety of Medicines and Health Products released a pharmacovigilance study report which analyzed over 14 millions prescriptions of etifoxine between 2000 and 2012 and found that adverse drug effects were 21 per million (0.0021%) patients. The report found no cases of abuse, misuse or pharmacodependence of etifoxine reported in over 14 million prescriptions analyzed.

Etifoxine is not designated as a controlled substance in France or any other country in which it is sold.

“No cases of abuse, misuse or pharmacodependence in over 14 million prescriptions analyzed.”