NSI-189 (NSI-189 Phosphate) Research Overview (also known as NSI-189 Phosphate, Neuralstem NSI-189)
NSI-189 phosphate is an investigational benzylpiperazine aminopyridine developed by Neuralstem Inc.; it is not a racetam. Preclinical and early clinical research indicates that it may stimulate hippocampal neurogenesis and influence mood and cognition, and Phase I/II studies in major depressive disorder produced promising, although not definitive, antidepressant and procognitive signals.
What Is NSI-189 (NSI-189 Phosphate)?
NSI-189 is an investigational small-molecule neurogenic compound developed by Neuralstem Inc. The commonly studied pharmaceutical form is NSI-189 phosphate, a salt intended to improve handling and oral formulation. The compound was designed as a potential treatment for disorders involving impaired hippocampal structure or function, including major depressive disorder and cognitive dysfunction. Unlike conventional antidepressants, whose primary pharmacological targets often include serotonin, norepinephrine, or dopamine transporters and receptors, NSI-189 was developed around the idea that stimulating endogenous neural progenitor cells could promote structural and functional recovery in the hippocampus.
NSI-189 is not a racetam. It belongs to the benzylpiperazine aminopyridine chemical family and should not be categorized with piracetam, aniracetam, oxiracetam, pramiracetam, or other racetam derivatives. Its proposed activity is also distinct from the commonly discussed AMPA-receptor-modulating or ampakine-like mechanisms associated with some racetam-related compounds. Early Phase I and Phase II clinical trials evaluated NSI-189 phosphate in adults with major depressive disorder. Those studies reported acceptable short-term tolerability and signals involving depressive symptoms, cognition, and hippocampal-related measures, but the evidence remains preliminary and does not establish NSI-189 as an approved antidepressant, neuroprotective agent, or cognitive enhancer.
Research Indications
Major Depressive Disorder Research
Depressive symptom measures
A randomized phase II study in major depressive disorder evaluated oral NSI-189 phosphate and reported improvement on selected depression rating outcomes versus placebo; findings require replication.
Cognitive symptoms in depression
Exploratory clinical measures suggested possible effects on cognitive domains associated with depression, but the evidence base remains small and investigational.
Neurogenesis and Neuroplasticity
Hippocampal progenitor-cell models
NSI-189 was developed following preclinical observations of increased neural progenitor-cell proliferation and neurogenesis-related effects in experimental systems.
Stress-related structural changes
The proposed neuroplasticity mechanism is biologically plausible in mood-disorder research, but direct confirmation of hippocampal neurogenesis in treated humans is unavailable.
Cognition and Traumatic Brain Injury
Cognitive performance
Claims regarding memory, attention, or executive function are not established by adequate clinical trials in healthy individuals.
Brain-injury applications
Preclinical rationale has prompted interest in neurological recovery, but NSI-189 is not an approved treatment for traumatic brain injury or other neurological conditions.
Research Protocols
As reported in cited literature and research-community logs (see Research Citations below) — not a personal dosing recommendation.
| Research Application | Dose | Frequency | Route |
|---|
| Phase II low-dose arm | 40 mg/day | Once daily | Oral |
| Phase II divided-dose arm | 80 mg/day | 40 mg twice daily | Oral |
| Phase II higher-dose arm | 120 mg/day | 40 mg three times daily | Oral |
| Clinical-study duration | Protocol-dependent | Typically several weeks | Oral |
Timing
Published clinical research used daily oral administration with divided dosing in higher-dose arms. There is no approved dosing regimen, and food effects, optimal timing, and long-term use parameters have not been established.
Peptide Interactions
Formal combination safety data are limited. Avoid changing prescribed antidepressant therapy without clinician oversight; monitor for activation, mood destabilization, and adverse effects.
No adequate interaction studies establish safety with MAO inhibitors. Because both are used in mood-related contexts, concurrent use should be treated as medically supervised only.
Potentially overlapping effects on sleep, anxiety, agitation, heart rate, or blood pressure have not been systematically characterized.
Lithium has independent neuroplasticity and mood effects, but there are no robust clinical data defining the safety or benefit of combining it with NSI-189.
Avoid recreational co-use. Alcohol can worsen depression, impair cognition, and obscure adverse reactions to an investigational neuropsychiatric compound.
Individuals treated for bipolar-spectrum illness, psychosis, or severe mood instability should use only under specialist direction because activation risk and interactions are not well defined.
Reported Research Timeline
01Days 1–7 (reported in cited studies): published data do not establish a reliable acute subjective effect. Some individuals may notice no change; headache, fatigue, gastrointestinal effects, or sleep changes may occur.
02Weeks 2–3 (reported in cited studies): in clinical research, symptom ratings were assessed repeatedly rather than inferred from day-to-day sensations. Early changes, if present, are not proof of efficacy.
03Weeks 4–6 (reported in cited studies): this is the approximate interval over which controlled depression studies evaluated changes in mood and cognitive measures. Individual responses were variable.
04Weeks 6–12 (reported in cited studies): continued use should not be assumed safe or effective from short trials alone. Reassess mood, sleep, anxiety, and functional status with a clinician.
05Beyond 3 months: Long-term efficacy, withdrawal effects, reproductive safety, and chronic neuropsychiatric safety remain insufficiently characterized.
Safety Notes
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
NSI-189 phosphate is investigational and is not approved by the FDA or other major regulatory authorities for depression, cognition, or neurological recovery.
Human safety evidence is limited in size and duration; risks from prolonged exposure and unsupervised combinations are not adequately known.
Use particular caution with a history of bipolar disorder, mania, hypomania, psychosis, severe anxiety, or substance-use disorder.
Avoid use during pregnancy or breastfeeding and in children or adolescents because appropriate safety data are lacking.
Do not discontinue prescribed antidepressants, mood stabilizers, or other psychiatric medicines in favor of NSI-189 without prescriber guidance.
Seek Medical Attention If:
You develop suicidal thoughts, worsening depression, severe agitation, impulsive behavior, or marked behavioral changes.
You experience possible mania or hypomania, including decreased need for sleep, racing thoughts, grandiosity, or unusually risky behavior.
You have chest pain, fainting, severe palpitations, severe headache, confusion, or a seizure.
You develop signs of a serious allergic reaction, such as facial swelling, trouble breathing, widespread rash, or hives.
Quality Indicators
Verified Marker
Identity-specific certificate of analysis
Request a lot-specific COA identifying NSI-189 phosphate, its salt form, lot number, test date, and the laboratory or analytical method used.
Verified Marker
Independent HPLC or LC-MS identity testing
Prefer chromatographic purity testing paired with mass-spectrometric identity confirmation, rather than an unsupported percentage-purity claim.
Verified Marker
Heavy-metal and microbiological screening
For oral capsules or powders, documentation should include heavy-metal limits and appropriate microbial testing for the finished product.
Acceptable Range
Capsule fill-weight accuracy
Capsule labeling should clearly state milligrams of NSI-189 phosphate per capsule and distinguish active mass from excipients; batch-to-batch uniformity data are preferable.
Quality Concern
Research-only labeling without traceable testing
Avoid products lacking a verifiable lot number, third-party analytical report, manufacturer contact information, or consistency between the label and COA.
Research Citations
- A phase 2, double-blind, placebo-controlled study of NSI-189 phosphate, a neurogenic compound, in major depressive disorder
Fava, M., Freeman, M. P., Flynn, M., et al., 2016, Molecular Psychiatry - Requirement of hippocampal neurogenesis for the behavioral effects of antidepressants
Santarelli, L., Saxe, M., Gross, C., et al., 2003, Science - Antidepressants increase neural progenitor cells in the human hippocampus
Boldrini, M., Underwood, M. D., Hen, R., et al., 2009, Neuropsychopharmacology - A neurotrophic model for stress-related mood disorders
Duman, R. S., Monteggia, L. M., 2006, Biological Psychiatry - Adult hippocampal neurogenesis in depression
Sahay, A., Hen, R., 2007, Nature Neuroscience
Research Focus
neurogenesis, hippocampus, depression, MDD, BDNF, cognitive enhancement, PTSD
Frequently Asked Questions
What should researchers watch for with NSI-189 (NSI-189 Phosphate)?
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
What should researchers expect over time with NSI-189 (NSI-189 Phosphate)?
Days 1–7 (reported in cited studies): published data do not establish a reliable acute subjective effect. Some individuals may notice no change; headache, fatigue, gastrointestinal effects, or sleep changes may occur.
How is NSI-189 (NSI-189 Phosphate) typically administered in research?
As reported in cited literature and research-community logs (see Research Citations below) — not a personal dosing recommendation.
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