NYX-2925 — Safety, Research, Risks & Legal Status

Not medical advice. NYX-2925 is discussed here for informational and harm-reduction purposes only. We do not endorse use, and any dosing context is informational, not a protocol.

Also known as	NYX-2925; (2S,3R)-3-hydroxy-2-((R)-5-isobutyryl-1-oxo-2,5-diazaspiro[3.4]octan-2-yl)butanamide; DrugBank DB19149
Category	Research Chemical
Developer	Aptinyx Inc.
Chemical class	Spirocyclic beta-lactam; NMDA receptor allosteric modulator
Structural lineage	Derived from rapastinel (GLYX-13), originally isolated from a monoclonal antibody scaffold
FDA designation	Fast Track for painful diabetic peripheral neuropathy (granted 2018)
Development stage	Phase 2b completed enrollment (2021-2022); results not publicly disclosed as of July 2026
Phase 2a DPN result	Primary endpoint not met - no significant pain reduction vs. placebo in ~300-subject trial
US legal status	Not FDA-approved. Holds Investigational New Drug (IND) status in the United States. Not classified as a controlled substance, which distinguishes it from ketamine and other NMDA-targeting agents. No legal pathway for human use outside of approved clinical trials. Not available as a dietary supplement. Possession and use outside a clinical trial context would fall under unapproved drug regulations.

What is NYX-2925?

NYX-2925 is an investigational, orally bioavailable small molecule developed by Aptinyx Inc. as a novel NMDA receptor modulator. It belongs to the spirocyclic beta-lactam chemical class and is structurally derived from rapastinel (GLYX-13), itself originally isolated from a monoclonal antibody scaffold. Unlike classical NMDA receptor antagonists such as ketamine, NYX-2925 acts as an allosteric modulator rather than a channel blocker. Its primary development focus has been chronic neuropathic pain, specifically painful diabetic peripheral neuropathy (DPN) and fibromyalgia. As of mid-2026, the compound has completed Phase 2b enrollment but Phase 2b results have not been publicly disclosed.

How it works

NYX-2925 modulates NMDA receptor signaling through an allosteric site distinct from the competitive glutamate and glycine binding sites, operating instead through a glycine-site enhancement mechanism. Rather than blocking the ion channel, it appears to activate metabotropic NMDA receptor signaling cascades that facilitate recruitment of synaptic GluN2B-containing NMDA receptors and subsequent insertion of GluA1-containing AMPA receptors at synapses. This synaptic protein trafficking is consistent with long-term potentiation (LTP) induction and structural synaptic plasticity. Preclinical data demonstrated increases in dendritic spine dimensions 24 hours after a single dose, suggesting durable downstream structural remodeling rather than purely acute receptor occupancy effects. This mechanism is proposed to underlie both cognitive enhancement observed in animal models and analgesic effects in neuropathic pain models, though the precise translation to human pain relief remains unconfirmed given the Phase 2a primary endpoint failure.

Background & history

NYX-2925 was developed by Aptinyx Inc., a biopharmaceutical company that focused on NMDA receptor modulation for CNS and pain indications. The compound is a structural descendant of rapastinel (GLYX-13), a peptide NMDA modulator that was itself derived from a monoclonal antibody. Aptinyx received FDA Fast Track designation for NYX-2925 in painful diabetic peripheral neuropathy in 2018, signaling regulatory interest in the mechanism. Three Phase 1 studies were completed successfully, establishing a clean early safety profile. A Phase 2a study in approximately 300 subjects with DPN failed to meet its primary endpoint on pain reduction versus placebo - a significant setback. Despite this, Phase 2b studies in DPN (NCT04146896, approximately 305 subjects) and fibromyalgia (NCT04147858, approximately 305 subjects) were initiated, with enrollment completed in late 2021 and early 2022 respectively. As of July 2026, Aptinyx has not publicly released Phase 2b results, and no Phase 3 advancement or regulatory decisions have been announced. The company's pipeline status as of this writing is uncertain.

What the research says

Human evidence is limited and mixed. Three Phase 1 trials confirmed safety and tolerability at doses up to 200 mg daily for four weeks, with first-in-human pharmacokinetic profiling completed. A Phase 2a trial in painful DPN (approximately 300 subjects) failed its primary endpoint - NYX-2925 did not produce a statistically significant reduction in average pain compared to placebo, which is a meaningful negative signal in an adequately powered trial. Phase 2b studies in DPN and fibromyalgia completed enrollment in 2021-2022 but results remain unpublished as of mid-2026, which limits any updated efficacy assessment. Preclinical data in rodent models showed enhanced novel object recognition, improved emotional learning, increased structural synaptic plasticity, and rapid and long-lasting analgesia in neuropathic pain models, with a calculated therapeutic index exceeding 1000. Translation of these animal findings to human benefit has not yet been established. No cognitive or antidepressant indications have entered formal human trials.

Reported effects

Proposed analgesic effects in neuropathic pain (preclinical robust; human Phase 2a primary endpoint not met)
Synaptic plasticity enhancement - increased dendritic spine dimensions observed in preclinical models 24 hours post-dose
Facilitation of long-term potentiation (LTP)-like processes via AMPA receptor insertion (preclinical only)
Enhanced novel object recognition and emotional learning in rodent models (preclinical only)
No sedative, ataxic, or addiction-related effects observed in preclinical studies or Phase 1 trials
No dissociative or psychotomimetic effects reported (distinguishes it from ketamine-class NMDA antagonists)

Dosing & administration (informational)

Published Phase 1 literature describes oral doses ranging up to 200 mg daily studied for periods up to four weeks. These figures represent what was evaluated for safety in early clinical trials, not established therapeutic doses - no effective dose has been identified in humans given the Phase 2a endpoint failure. This information is provided for reference to the published clinical literature only. No dosing protocol or recommendation can be derived from available data, and no clinician-independent use is appropriate. Consult a licensed clinician for any pain or neurological condition.

This is general research/context information, not medical advice or a recommended protocol.

Safety & side effects

Phase 1 data (up to 200 mg daily for 4 weeks) showed no serious adverse events attributable to the drug
No controlled substance classification; no observed abuse potential signals in preclinical or clinical data
No sedation or ataxia reported across preclinical or early clinical programs
No significant safety signals emerged in Phase 2a DPN study (~300 subjects)
Long-term safety data beyond 4 weeks in humans is not available in published literature
Phase 2b safety data has not been publicly disclosed as of mid-2026
Preclinical therapeutic index reported as greater than 1000, suggesting a wide safety margin in animal models

Drug & supplement interactions

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Who should avoid it

Any combination with NMDA antagonists (ketamine, memantine, PCP, dextromethorphan) - theoretical pharmacodynamic overlap, no safety data
Use outside of a supervised clinical trial - no approved indication exists
Sourcing from non-clinical-trial supply chains - identity and purity cannot be confirmed
Use in pregnancy or lactation - no reproductive safety data available
Substituting for established, guideline-recommended treatments for DPN or fibromyalgia

How it is commonly combined

No stacking information exists in the peer-reviewed or clinical trial literature. NYX-2925 has only been studied as monotherapy in clinical trials. No combination data with other analgesics, antidepressants, anticonvulsants, or nootropic compounds has been published. Any combination use would be entirely experimental and unsupported by evidence.

Legal & regulatory. Not FDA-approved. Holds Investigational New Drug (IND) status in the United States. Not classified as a controlled substance, which distinguishes it from ketamine and other NMDA-targeting agents. No legal pathway for human use outside of approved clinical trials. Not available as a dietary supplement. Possession and use outside a clinical trial context would fall under unapproved drug regulations.

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Frequently asked questions

What is NYX-2925 and how does it differ from ketamine?

NYX-2925 is an oral NMDA receptor allosteric modulator, meaning it modifies receptor function indirectly through a binding site distinct from the ion channel pore. Ketamine blocks the NMDA receptor channel directly (open-channel block), producing anesthesia, dissociation, and abuse potential. NYX-2925 has shown no sedative, dissociative, or addictive properties in preclinical or Phase 1 data. The two compounds share a target receptor family but operate through different mechanisms with different profiles.

Did NYX-2925 work in human clinical trials?

The available evidence is negative to inconclusive. A Phase 2a trial in painful diabetic peripheral neuropathy (approximately 300 subjects) failed its primary endpoint - the drug did not significantly reduce pain versus placebo. Phase 2b trials in DPN and fibromyalgia completed enrollment in 2021-2022, but results have not been publicly released as of July 2026. Until those data are disclosed, a full efficacy assessment is not possible.

Is NYX-2925 available to purchase or use outside a clinical trial?

No. NYX-2925 holds IND status only and has never been approved by the FDA. It is not available through any legal consumer channel, including compounding pharmacies or supplement suppliers. Any material labeled as NYX-2925 sold outside a clinical trial context would be of unverifiable identity and purity. Human use outside a supervised clinical trial is without regulatory basis.

What were the preclinical findings for NYX-2925?

In rodent models, NYX-2925 demonstrated analgesic effects in neuropathic pain paradigms, enhanced novel object recognition, improved emotional learning, and increased dendritic spine dimensions 24 hours after dosing - suggesting lasting structural synaptic changes. A preclinical therapeutic index exceeding 1000 was reported. These results were promising but did not fully predict the Phase 2a human trial outcome, which is not unusual given the general difficulty of translating rodent pain model findings to clinical benefit.

What is the current development status of NYX-2925?

As of July 2026, Phase 2b trials in DPN and fibromyalgia completed enrollment in 2021 and 2022 respectively, but Aptinyx has not publicly released results. No Phase 3 advancement or regulatory filings have been announced. The program appears stalled or paused. The company's current operational status and pipeline prioritization are not clearly reflected in recent public disclosures.

Can NYX-2925 be used for cognitive enhancement or nootropic purposes?

There are no human trials supporting cognitive enhancement use. Preclinical rodent data showed improvements in novel object recognition and emotional learning tasks, which motivated early interest in CNS applications, but these findings have not been tested in human trials designed for cognitive endpoints. Extrapolating rodent cognition data to human use would be speculative and unsupported by clinical evidence.

References & further reading

PubMed: NYX-2925 NMDA receptor spirocyclic beta-lactam synaptic plasticity (see PMID 29099938)
PubMed: NYX-2925 first-in-human safety pharmacokinetics (see PMID 30242962)
PubMed: NYX-2925 neuropathic pain analgesia JPET 2018 (see PMC7065110 / JPET 366:3)
ClinicalTrials.gov: NCT04146896 (Phase 2b painful diabetic peripheral neuropathy)
ClinicalTrials.gov: NCT04147858 (Phase 2b fibromyalgia)