Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Head-to-head comparison of NSI-189 and PRL-8-53 — mechanism, side effects, legal status, and pricing.
NSI-189 (INN: amdiglurax; developmental code ALTO-100) is a non-peptide small-molecule benzylpiperazine-aminopyridine derivative investigated as a neurogenic/neuroplasticity-modulating agent for major depressive disorder. It stimulates hippocampal neural progenitor proliferation and differentiation in vitro and neurogenesis in vivo (mouse), acting independently of monoamine reuptake pathways. NSI-189 has never been FDA-approved; Phase 2 monotherapy trials in MDD (220 patients, 2020) and a Phase 2b trial under Alto Neuroscience (~300 patients, 2024) both failed to meet primary MADRS endpoints, and it remains investigational only.
PRL-8-53 is a non-peptide small-molecule aminoalkyl benzoic acid ester (methyl benzoate derivative), supplied as the hydrochloride salt. Originally characterized in 1974 animal studies as a spasmolytic and CNS-active agent, it has never been approved by any regulatory agency and is sold only as a research chemical. Exactly one published human trial exists—a 1978 double-blind study on verbal learning and retention—with no independent replication or modern safety data.
NSI-189
PRL-8-53
Category
Legal Status
Mechanism
Side Effects
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NSI-189
No pricing data yet.
Check NSI-189 prices →PRL-8-53
COA corpus from Disclosed Labs — independently tested batches only.
NSI-189
No COA data yet.
Submit testing data →PRL-8-53
3
COAs
96.8%
Avg purity
2
Labs
Human data exist from three registered trials: a Phase 1 single-dose PK study in healthy volunteers (NCT01310881), a Phase 1B multiple-dose-escalation study in 24 MDD patients (28-day inpatient dosing at 40 mg once/twice/thrice daily; half-life ~17.4–20.5 hours; no serious adverse events; no significant hippocampal volume change at day 28 or 84), and a Phase 2 double-blind, placebo-controlled trial in 220 MDD outpatients (12 weeks at 40 mg or 80 mg daily) that missed its primary MADRS endpoint at both doses (p=0.22 and p=0.34, respectively), with some significant secondary/patient-reported benefits at 40 mg. A Phase 2b trial under the ALTO-100 designation (~300 adults, 34 US sites, 6-week double-blind) also failed to meet its primary MADRS endpoint (topline October 2024). Preclinical findings include improved motor/neurological deficits sustained to 24 weeks in a rat stroke model (oral dosing starting 6 hours post-MCAO; increased hippocampal/cortical MAP2 neurite outgrowth; in vitro OGD/R assays showed reduced cell death and upregulated BDNF/SCF), reversal of motor and cognitive impairments in an Angelman syndrome mouse model (with mild performance enhancement in wild-type mice), improved Barnes maze memory retention in a 5xFAD Alzheimer's mouse model (conference abstract), and prevention of peripheral neuropathy indices with increased hippocampal neurogenesis/synaptic markers/volume and protected long-term memory in mouse and rat models of type 1 and type 2 diabetes, alongside enhanced mitochondrial function in a type 2 diabetic rat model.
Key references
Exactly one published human study was located: a 1978 double-blind trial (Hansl & Mead, <em>Psychopharmacology</em>, PMID 418433) using the serial anticipation method to test oral PRL-8-53 on verbal learning acquisition and retention, with follow-up on visual reaction time and motor control; the study reported statistically significant retention improvement (most P<0.01) and no significant reaction-time or motor effects, but sample size and exact dose are not stated in the available abstract. No further human trials were found, and no ClinicalTrials.gov entries exist. Preclinical work is limited to the 1974 Hansl paper (PMID 4824605) in dogs and rats, indexed for avoidance learning, conditioning, memory, and pharmacological interaction with apomorphine and methamphetamine, though full quantitative findings could not be verified because no abstract text is available.
NSI-189 and PRL-8-53 are both in the Cognitive category and may have overlapping mechanisms. Researchers should review both profiles carefully, understand the mechanisms of action, and monitor the relevant biomarkers when combining compounds in the same class. As always, consult a licensed healthcare provider before making any decisions about combining research compounds.
This platform provides informational tools only, not medical advice. This comparison is for educational purposes only. Consult a licensed provider.
Contraindications
Lab Testing
Disclosed Labs