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zelquistinel (codes GATE-251 and AGN-241751) is an investigational oral drug for depression; it is a positive allosteric modulator of the NMDA glutamate receptor, from the same 'rapastinel' lineage of NMDA-modulating antidepressants. the idea is a ketamine-style rapid and durable antidepressant effect via enhanced synaptic plasticity, but as a pill and without the dissociative high. it is not a classic pregnane neurosteroid; it is included as a glutamatergic modulator alongside them. it is in phase 2 testing for major depressive disorder.
- Oral, take-home NMDA modulator (no infusion)
- Rapid and sustained antidepressant-like effects in animals
- Aims for ketamine-like benefit without dissociation or abuse liability
- Works by enhancing synaptic plasticity (LTP)
- unlike ketamine, it enhances NMDA receptors instead of blocking them, aiming for the mood benefit without the dissociation.
- it comes from the same chemical family as rapastinel (GLYX-13), whose phase 3 depression trials failed, which is why the bar is high.
- in animals a single low oral dose produced rapid and long-lasting antidepressant-like effects.
- it has had three names across three companies: AGN-241751 (Allergan era), GATE-251 (Gate), now developed by Syndeio.
Mechanism
zelquistinel is an orally bioavailable positive modulator of the receptor, descended from the GLYX-13/rapastinel program (spiro-beta-lactam NMDA modulators). rather than blocking the channel the way ketamine does, it enhances function at a novel allosteric site and, downstream, boosts activity-dependent , the cellular form of strengthening thought to underlie the durable antidepressant effect of this class. in rodent models a single low oral dose produced rapid and sustained antidepressant-like effects (forced swim, chronic social defeat) at exposures that increased NMDA function and , and it did not produce the phencyclidine-like hyperlocomotion or motor impairment associated with NMDA antagonists, suggesting a cleaner behavioural profile than dissociatives. the clinical hope is a take-home pill that delivers ketamine-like speed and durability without the dissociation, sedation or abuse liability. the reality is early: it advanced through phase 1 and small phase 2 work as AGN-241751 (originally Allergan/Aptinyx-adjacent chemistry, then Gate Neurosciences, now Syndeio Biosciences) and is in ongoing phase 2 trials for major depressive disorder. efficacy in humans is not yet established.
receptor fingerprint
novel-site positive allosteric modulator; enhances NMDA function and activity-dependent long-term potentiation rather than blocking the channel
plasticity ()enhances activity-dependent long-term potentiation in hippocampus and prefrontal cortex
Safetyrisks and cautions, not medical advice
as an investigational compound, zelquistinel's human safety is still being characterised in phase 1/2 trials; the pitch is that as an NMDA positive modulator it avoids the dissociation, sedation and abuse potential of NMDA-blocking dissociatives like ketamine, and preclinical work did not show PCP-like effects. that said, it is unapproved, human efficacy is unproven, and any glutamatergic drug warrants caution about excitotoxicity and CNS effects until larger trials report. it is not available as a legitimate product; material sold as 'zelquistinel' online is unvalidated.
History
the molecule traces to the rapastinel (GLYX-13) NMDA-modulator lineage. it was studied as AGN-241751 in early Allergan-era trials for major depressive disorder, then carried forward by Gate Neurosciences as GATE-251, and is now developed by Syndeio Biosciences, which has active phase 2 depression trials. it reflects the field's continued interest in NMDA/glutamate modulation for rapid-acting antidepressants after ketamine and esketamine.
Reputation
in the rapid-antidepressant space zelquistinel is a credible but unproven candidate; the class (rapastinel) famously failed its phase 3 depression trials, so there is healthy skepticism about whether NMDA positive modulators can beat placebo in humans despite strong rodent data. it is a compound to watch, not a validated treatment, and it has no nootropic or consumer use.
Subjective profileweighing the evidence above
Worth watching, not worth buying. An oral NMDA positive modulator aiming for ketamine-like relief without the dissociation is a genuinely good idea, but human efficacy is unproven, the rapastinel lineage it comes from already failed phase 3, and material sold online under the name is unvalidated.
Resources
This entry is here for reference.
Research
- 1.Zelquistinel Is an Orally Bioavailable Novel NMDA Receptor Allosteric Modulator That Exhibits Rapid and Sustained Antidepressant-Like Effects.
- 2.Phase 2 randomized double-blind evaluation of oral zelquistinel (GATE-251) for major depressive disorder (NCT06547489)
- 3.Two-part phase 1/2 study of AGN-241751 (zelquistinel) in adults with major depressive disorder (NCT03726658)
3 listed here; entry last updated August 2026
Reviews
My notesprivate to this device
FAQ
What is zelquistinel?
an investigational oral drug for depression that positively modulates the NMDA glutamate receptor, from the same lineage as rapastinel. it is in phase 2 testing.
How is it different from ketamine?
ketamine blocks NMDA receptors and causes dissociation; zelquistinel enhances NMDA receptor function at a different site, aiming for the antidepressant benefit without the dissociative high or abuse potential.
Does it work in people?
not established yet. rodent data are strong, but the related drug rapastinel failed its phase 3 depression trials, so human efficacy is a genuine open question that current phase 2 trials are testing.
Is it a neurosteroid?
no; it is a synthetic NMDA modulator, grouped here alongside neurosteroids because both classes are being pursued as rapid-acting, plasticity-based antidepressants.
Can I get it?
no; it is an unapproved investigational compound. anything sold under that name is unvalidated and not a real medicine.
Why do people care about NMDA modulators for depression?
because ketamine showed that glutamate-system drugs can lift depression within hours and boost synaptic plasticity; the field is chasing a safe, oral, take-home version of that effect.
Limitations of the evidence
- Investigational; human efficacy unproven
- Class (rapastinel) previously failed phase 3
Notes and cautions
- Unapproved and not legitimately available
- Long-term glutamatergic safety not established