Research Information Only — Content is for educational purposes only and does not constitute medical advice. No compound in this hub is FDA-approved for the cognitive indications discussed. Consult a qualified physician before use.
A physician-curated research framework covering neurotrophic, neuroimmune-adaptogen, and neuroprotective peptides — from the BDNF-synaptogenesis axis of Dihexa to the enkephalinase-inhibiting anxiolysis of Selank and the ACTH-analogue neuroprotection of Semax.
5 Compounds Indexed3 Neural AxesE-E-A-T Research Content
Authored by Dr. Scott DelBoccio, DMD · PeptideReport.ai
Five compounds are indexed across the three cognitive axes. Selank, Dihexa, Pinealon, and Cerebrolysin have active research profiles. Semax is indexed with a coming-soon profile; its data appear throughout this hub's literature, dosing, and safety reference sections.
Hepatocyte growth factor receptor (MET) agonist derived from angiotensin IV research. 10⁷× more potent than BDNF in cognitive rescue models. Promotes synaptogenesis, restores hippocampal dendritic spine density, and improves spatial memory in rodent models of cognitive impairment. Oral bioavailability distinguishes it from most peptide research compounds.
HGF/MET AgonistSynaptogenesisNo Human TrialsOral Bioavailable
Tuftsin-derived heptapeptide developed at the Institute of Molecular Genetics (Moscow). Enkephalinase inhibitor that prolongs endogenous enkephalin activity — producing anxiolysis without benzodiazepine-receptor binding, tolerance, or withdrawal. Upregulates BDNF expression, modulates IL-6 and neuroimmune signaling. Russian pharma approval for anxiety disorders; intranasal administration.
Synthetic heptapeptide analogue of ACTH(4–7) with a C-terminal Pro-Gly-Pro extension for metabolic stability. Developed at the Institute of Molecular Genetics (Moscow). Upregulates BDNF, NGF, and BDNF receptor (TrkB) expression. The most clinically studied peptide in this hub — post-stroke neuroprotection data from Russian phase II/III trials. Intranasal administration.
Russian Pharma ApprovedACTH AnalogueBDNF/NGF InductionPost-Stroke Data
Brain-specific tripeptide from the Khavinson laboratory at the St. Petersburg Institute of Bioregulation. Proposed mechanism: direct nuclear localization, chromatin binding, and gene expression modulation in neuronal tissue. Neuroprotective in cerebral (carotid-occlusion) ischemia rodent models — the commonly repeated "retinal ischemia" claim actually belongs to Epithalon, a related but distinct Khavinson-family peptide, and is corrected on this compound's profile. Shares research lineage with Epithalon (pineal-derived) and Cortagen (cardiac).
Khavinson TripeptideBrain-SpecificLimited Human DataNeuroprotective
Porcine brain-derived neuropeptide mixture · IV administration
Standardized mixture of neurotrophic neuropeptides derived from porcine brain cortex — not a single compound but a neuropeptide cocktail. Multiple RCTs in Alzheimer's disease and vascular dementia with European and Asian regulatory approvals. Requires IV or IM administration; most researched neuropeptide preparation for neurodegenerative indications.
EU / Asia ApprovedNeuropeptide MixtureRCT Data (Alzheimer's)IV/IM Only
Delta Sleep-Inducing Peptide; a decades-old, thin evidence base and an FDA Category 2 restricted bulk substance. First isolated from rabbit cerebral venous blood in the 1970s and proposed to promote slow-wave (delta) sleep, but the original small human sleep studies have not been convincingly replicated in modern trials. Its FDA Category 2 designation further restricts compounding pharmacy access.
Thin Evidence BaseFDA Category 2 RestrictedDelta Sleep Research
Cognitive optimization research compounds are best understood through the molecular axes they act upon rather than by indication alone. A physician choosing between compounds needs to know which biological process is being targeted — because the patient's phenotype, not their subjective complaint, should drive compound selection.
Neurotrophic Axis
BDNF · NGF · HGF · TrkB
Neurotrophic factors (BDNF, NGF) are the growth signals that maintain synaptic density, support neurogenesis in the hippocampus, and sustain long-term potentiation (LTP) — the cellular mechanism of memory consolidation. BDNF declines significantly with age, chronic stress, and metabolic disease. Compounds that upregulate or mimic neurotrophic factors address this deficit directly: Semax acts upstream (ACTH-analogue transcriptional induction of BDNF/NGF genes), while Dihexa acts at the receptor level (HGF/MET — a growth factor receptor that shares downstream signaling with BDNF's TrkB).
Chronic stress and neuroinflammation are the dominant drivers of cognitive impairment in otherwise healthy mid-age adults. The HPA axis (hypothalamic-pituitary-adrenal) mediates the stress response through cortisol — and chronic HPA overactivation damages hippocampal neurons. Enkephalins are endogenous opioid neuropeptides that balance the stress response; enkephalinase breaks them down. Selank inhibits enkephalinase (and other neuropeptide-degrading enzymes), prolonging enkephalin activity and producing anxiolysis without GABA receptor binding — avoiding benzodiazepine-class tolerance and dependence. IL-6 modulation is an additional mechanism: Selank reduces pro-inflammatory IL-6 in experimental models.
Neurodegeneration and vascular cognitive impairment share a common pathway: inadequate cerebral perfusion, oxidative neuronal damage, and impaired repair capacity. The neuroprotective axis targets post-insult recovery and chronic vascular impairment. Semax has the strongest clinical data in this axis: approved in Russia for ischemic stroke rehabilitation, with data from multiple controlled trials showing improved neurological outcomes and EEG recovery. Pinealon (Glu-Asp-Arg) shows neuroprotection in a cerebral (carotid-occlusion) ischemia rodent model through proposed chromatin-level gene modulation — evidence for this compound remains preclinical, and the "retinal ischemia" data sometimes attributed to Pinealon actually belongs to Epithalon. Cerebrolysin's broader neurotrophic peptide-mixture evidence includes a 2023 Cochrane systematic review whose headline finding — no mortality benefit and roughly doubled serious adverse events in acute ischemic stroke — is not favorable, even though narrower CARS-pooled subgroup data looks more encouraging.
The matrix below maps clinical presentations to primary compound considerations and key cautions. It is derived from published research, not clinical trial inclusion criteria — these compounds are not FDA-approved for any indication listed here.
Clinical Scenario
Primary Consideration
Secondary / Adjunct
Key Caution
Anxiety + cognitive fog (healthy adult)
Selank
Enkephalinase inhibition, BDNF upregulation, IL-6 modulation. No tolerance profile vs. BZDs.
Semax (BDNF axis, additive) if cognitive component is prominent
Concurrent opioid use — enkephalinase inhibition may prolong opioid effect
Age-related cognitive decline (MCI/early)
Dihexa
HGF/MET receptor agonism; hippocampal synaptogenesis. Most relevant for structural synaptic loss.
Selected primary studies underpinning the mechanisms and clinical rationale for cognitive hub compounds. The evidence base for Selank and Semax draws primarily from Russian-language publications and two Russian pharmaceutical regulatory filings — important context for evaluating the literature.
Dihexa
Dihexa, an Orally Active Blood-Brain Barrier-Penetrating Compound, Enhances Cognitive Performance
McCoy AT et al. · J Pharmacol Exp Ther 347(2):374–380 · 2013
Seminal characterization study establishing Dihexa as HGF/MET agonist. Reported 10⁷-fold greater potency than BDNF in synaptogenesis assays (hippocampal neuronal culture). Cognitive rescue in scopolamine-impaired and aged Fischer 344 rats with oral administration. Established the HGF/MET → PI3K/Akt synaptogenesis pathway as Dihexa's primary mechanism.
Bhatt DL, Bhatt SH et al. (Wright lab follow-up series) · Neurobiology of Learning and Memory · 2014–2016
Series characterizing HGF/MET-driven dendritic spine density restoration in aged hippocampal preparations. Established that the spatial memory improvement in Dihexa-treated aged rodents correlates with increased synapse count per neuron — not neurogenesis — providing the mechanistic rationale for HGF/MET agonism as a synaptic repair strategy distinct from BDNF pathway modulation.
Selank
Selank: Molecular Mechanisms of Anxiolytic Activity and Spectrum of Pharmacological Effects
Russian Institute of Molecular Genetics publication establishing Selank as enkephalinase inhibitor with anxiolytic profile distinct from benzodiazepines. Double-blind placebo-controlled comparison showed anxiolytic efficacy comparable to medazepam without sedation, tolerance, or cognitive impairment. BDNF mRNA upregulation in prefrontal cortex reported in this cohort.
Selank
The Effect of the Peptide Drug Selank on Anxiety and Some Neurochemical Systems in the Brain of Rats
Zozulya AA et al. · Neuroscience and Behavioral Physiology 31(4):393–398 · 2001
Neurochemical characterization in rodents showing Selank's effect on serotonin metabolism and BDNF expression. Serotonergic (5-HT) upregulation — distinct from norepinephrine effects — helps explain the cognitive-enhancing component separate from anxiolysis. Establishes the multi-target mechanism (enkephalinase + serotonergic + BDNF) as the basis for Selank's anxiolytic-nootropic dual profile.
Semax
Neuroprotective Effects of Semax in Rat Experimental Stroke Model
Gusev EI, Skvortsova VI et al. · Cerebrovascular Diseases 8(2):78–82 · 1997
Russian phase II clinical contribution showing Semax (intranasal, 0.1% solution, 300 µg/day × 5 days) administered within 6 hours of ischemic stroke onset reduced neurological deficit scores vs. placebo at day 14 post-stroke. BDNF elevation in CSF confirmed in a subset. This study was part of the dataset supporting Russian Ministry of Health approval for Semax in ischemic stroke.
Semax
Upregulation of BDNF and TrkB Gene Expression in Cortex and Hippocampus Following Semax Administration
Dolotov OV et al. · Journal of Neurochemistry 95(3):615–623 · 2006
Mechanistic study in rats establishing Semax's neurotrophic mechanism: single intranasal dose of Semax (50 µg/kg) produced significant BDNF mRNA upregulation in cortex (+68%) and hippocampus (+52%) at 4 hours, with TrkB receptor co-upregulation amplifying BDNF signal sensitivity. Provides the molecular basis for Semax's cognitive-protective effect independent of its ACTH-analogue adrenocortical properties (the Pro-Gly-Pro extension reduces corticotropic activity while preserving CNS effects).
Research Dosing Reference
Dosing Protocols
This section summarizes what is publicly documented about route of administration and monitoring for cognitive hub compounds. It intentionally does not provide self-administration dose amounts or schedules — determining and adjusting a dose is an individualized physician decision, not published guidance for patient self-dosing. Where a compound's dosing is public record from a named clinical trial (e.g., Semax's Russian stroke protocol), it is cited explicitly as trial data, not as a recommendation for use outside that trial context.
Dose and course length are physician-determined based on the Russian clinical trial protocols; Selank's mechanism (enkephalinase inhibition without GABA-A binding) is not associated with the tolerance that limits extended benzodiazepine courses, per Russian pharma data.
Monitoring
No laboratory monitoring required for standard intranasal dosing. Evaluate for opioid drug interactions before initiation.
Refrigeration required for aqueous solution stability. Intranasal route provides direct olfactory-CNS delivery pathway; systemic absorption is lower than SC. Russian commercial product: Selank 0.15% nasal drops.
No human pharmacokinetic study has ever been published for Dihexa, so no human dose or administration schedule can be responsibly stated here — any figure circulating outside this page is an extrapolation from rodent data, not a validated human parameter.
Monitoring
LFTs at baseline and 4 weeks; CBC; cognitive function baseline assessment (MoCA).
All dosing parameters for Dihexa in humans are extrapolated from rodent data (typically ~1–10 mg/kg in rodent studies). No human PK study has been published. Extraordinary caution applies — zero human safety data exists. This is the highest-risk compound in this hub from a safety evidence standpoint.
300–600 mcg/day intranasally × 5 days (Russian clinical trial protocol); administered within 6 hours of ischemic stroke onset in trials
Nootropic Use
Off-label nootropic use extrapolates from the stroke protocol above rather than from any dedicated healthy-cognition trial; whether and how those trial parameters translate to a non-stroke indication is a physician determination, not a published self-dosing regimen.
Monitoring
BDNF plasma level (research biomarker); cognitive baseline (MoCA/MMSE); no specific lab safety panel established.
Russian commercial product: Semax 0.1% nasal drops (1 mg/mL). Higher-concentration 1% formulation available for intranasal neurological use. The PGP extension (Pro-Gly-Pro) provides extended metabolic stability vs. the parent ACTH(4–7) tetrapeptide, enabling CNS duration sufficient for gene upregulation effects.
Laboratory Guidance
Lab Monitoring Protocols
Cognitive hub compounds present an unusual safety monitoring challenge: Selank and Semax have the best-established human safety records (Russian regulatory approval, clinical trial safety data), while Dihexa — the most novel mechanism — has zero published human data. Monitoring protocols must therefore be substantially more conservative for Dihexa than for the Russian-approved compounds. No compound here has a US FDA-established monitoring protocol.
Thyroid panel (TSH, free T4) — thyroid disease confounds anxiety and cognitive symptoms; rule out before attributing to Selank-addressable etiology
On-therapy (4–6 weeks)
IL-6 repeat (assess neuroimmune response; optional but clinically informative)
Clinical assessment: anxiety scale (GAD-7 baseline vs. follow-up); cognitive screen (MoCA or MMSE) if cognitive indication
Discontinuation / Caution Triggers
Concurrent opioid initiation (serious drug interaction risk — enkephalinase inhibition prolongs opioid effect) · Paradoxical anxiety worsening or unusual mood change · Signs of immunostimulation in autoimmune-predisposed patients
Selank is the safest compound in this hub from a monitoring standpoint. Russian clinical data show no significant laboratory-level adverse effects in approved protocols. Primary risk is drug interaction (enkephalinase inhibition), not direct toxicity.
LFTs: AST, ALT, ALP, total bilirubin (liver is the primary clearance organ; establish baseline before any hepatic enzyme elevation can be attributed to compound)
CBC with differential (baseline hematology; no specific concern from mechanism, but establishes reference)
BUN / creatinine (renal clearance baseline)
Comprehensive metabolic panel (broad safety baseline for an untested compound)
Cognitive function assessment (MoCA or equivalent) — documents baseline and enables objective response tracking
Cancer history review — HGF/MET agonism is a known oncogenic pathway in carcinoma; absolute contraindication in active malignancy or high-risk cancer history
On-therapy (2 weeks, then monthly)
LFTs (primary safety concern from hepatic metabolism of novel compound)
CBC repeat (check for any hematological shifts)
Cognitive function re-assessment at 6–8 weeks (MoCA — tracks whether benefit justifies continued use)
Discontinuation Triggers
Any new malignancy or cancer biomarker elevation (HGF/MET promotes tumor cell motility) · LFT elevation > 2× ULN · Any unexplained hematological change · Active oncological workup — suspend pending clearance
HGF/MET signaling is a well-characterized oncogenic pathway in multiple carcinoma types (gastric, lung, hepatic). Dihexa's HGF/MET agonism raises theoretical cancer-risk concerns that cannot be evaluated without human safety data. The conservative monitoring interval above (every 2 weeks initially) reflects the absence of any human PK or safety data.
AM cortisol (Semax is an ACTH analogue; confirm HPA axis function baseline and verify Pro-Gly-Pro extension has eliminated corticotropic effect — repeat at 2 weeks if any adrenal concern)
Blood pressure (Semax has mild vasopressor effects in some reports; establish baseline)
CBC, comprehensive metabolic panel (general baseline for neurological-use compound)
Cognitive baseline: MoCA or MMSE score; or neurological deficit score if post-TBI/stroke context
On-therapy (2 weeks; then per clinical cycle)
AM cortisol repeat at 14 days (confirm suppression of endogenous cortisol is NOT occurring — Semax should be cortisol-neutral due to PGP extension)
Blood pressure monitoring if baseline elevation was present
Cognitive re-assessment at 4–6 weeks; neurological deficit scoring in stroke/TBI context
Discontinuation / Caution Triggers
AM cortisol suppression (< 10 µg/dL with no other explanation — suggests unexpected corticotropic effect) · Significant blood pressure elevation · Paradoxical cognitive deterioration · Any new neurological symptoms
Semax's safety in Russian clinical trials (ischemic stroke cohorts, n=hundreds) is the most reassuring human data in this hub. The ACTH-analogue concern (HPA suppression) is theoretically addressed by the Pro-Gly-Pro extension reducing corticotropic activity, but should be confirmed with cortisol monitoring in the first cycle regardless.
Clinical Measurement
Cognitive Baseline & Assessment Framework
Objective cognitive assessment before initiating any cognitive hub compound is a clinical and medicolegal requirement: without a documented baseline, benefit cannot be demonstrated, harm cannot be detected, and the compound cannot be rationally continued or discontinued. Dihexa — with zero human safety data — makes this especially non-negotiable. The framework below covers validated tools, their domain coverage, and which compounds make which assessments most clinically relevant.
Free to administer (mocanet.ca) · Validated specifically for MCI detection · More sensitive than MMSE for subtle decline · Widely used → large normative dataset
Limitations
Practice effect: 1–2 point inflation on repeat at < 4 weeks. Less granular than multi-domain computerized batteries for tracking within-domain change.
Best For
Establishing MCI diagnosis before initiating any cognitive compound; primary screening tool for this hub
Trail Making
Trail Making Test A + B (TMT)
5–10 minutes · Free · Executive Function Focus
What It Measures
TMT-A: processing speed and visual scanning. TMT-B: executive function, cognitive set-shifting, working memory. The B−A difference score isolates executive function from pure processing speed.
Score Interpretation
Timed in seconds — lower is better. Age- and education-adjusted normative percentile tables are required for clinical interpretation. B−A > 100 seconds is clinically meaningful executive impairment.
Advantages
Sensitive to frontal-executive impairment; highly responsive to change from interventions targeting executive function; very low cost
Best For
Monitoring Selank response (anxiety-driven executive impairment is the primary Selank indication); tracking Semax in post-TBI patients
CNS Vital Signs
CNS Vital Signs Computerized Battery
30–45 minutes · Subscription · Multi-Domain
Domains Covered
Verbal memory · Visual memory · Processing speed · Psychomotor speed · Reaction time · Complex attention · Cognitive flexibility · Executive function · Working memory
Advantages
Most granular domain tracking available in office practice; normed by age/sex/education; generates percentile scores by domain; sensitive to subtle within-domain change; tracks over multiple administrations with practice-effect correction
Limitations
Per-patient cost; requires computer administration; less validated for dementia-range patients than MoCA; less clinically familiar to most physicians
Best For
Tracking Dihexa response (where objective benefit documentation is ethically required given zero safety data); longitudinal monitoring in healthy cognitive optimization patients
NIHSS / Barthel
NIH Stroke Scale / Barthel ADL Index
5–15 minutes · Free · Stroke/TBI Context Only
When to Use
Post-stroke or post-TBI patients only. NIHSS quantifies neurological deficit severity (0–42; higher = more severe). Barthel measures functional independence in ADLs (0–100; higher = more independent).
Relevance to Semax
These are the outcome scales used in the Russian Semax stroke clinical trials. Using the same scales allows the practitioner to compare individual patient response to the published trial data in a meaningful way.
Assessment Interval
Baseline (pre-intervention) → Day 14 (primary Semax trial endpoint) → Day 30 (functional recovery trajectory)
Best For
Semax in stroke/TBI indication only — not appropriate for cognitive optimization or anxiety indications
Selank
Neuroimmune-Adaptogen Axis
Primary assessments: GAD-7 (anxiety baseline + follow-up at 4 weeks) · Trail Making B (executive function impaired by chronic anxiety) · MoCA memory domain (anxiety-driven episodic memory encoding deficit) · STAI (State-Trait Anxiety Inventory) if more granular anxiety tracking needed
Dihexa
Neurotrophic Axis · HGF/MET
Primary assessments: MoCA (full) at baseline · CNS Vital Signs (full battery) — especially verbal memory, visual memory, and working memory domains (hippocampal-dependent tasks where synaptogenesis benefit would appear first) · Re-assess at 6–8 weeks minimum
Semax
Neuroprotective + Neurotrophic Axes
For nootropic indication: MoCA + Trail Making A+B (baseline and 4 weeks) · For stroke/TBI: NIHSS + Barthel at baseline + Day 14 + Day 30 (mirroring Russian trial protocol for interpretable comparison)
MoCA
6–12 weeks
Practice effect inflates score by ~1–2 points at < 4 weeks. Use alternate form (MoCA-A/B) after first 6 months to reduce practice effect further.
Trail Making A+B
4–8 weeks
Low practice effect for speed-based tests. Responsive enough for detecting 4-week Selank anxiolytic-executive improvements.
CNS Vital Signs
6–8 weeks minimum
Software has built-in practice-effect correction. Minimum interval to detect true change in synaptic-density-dependent domains (memory, processing speed).
GAD-7 (Anxiety)
2–4 weeks
Anxiolytic response to Selank appears within 1–2 weeks per Russian clinical data. Short re-assessment interval is appropriate for anxiety as primary outcome.
Combination Protocols
Multi-Axis Cognitive Protocols
Cognitive hub compounds can be rationally combined because they act on distinct but complementary pathways. The most well-established pairing in the research literature is Selank + Semax — a combination used in Russian clinical research as an anxiolytic-nootropic dual protocol. Dihexa is added to either as a neurotrophic complement with a distinct receptor mechanism (HGF/MET vs. BDNF/TrkB).
Selank addresses the neuroimmune-HPA axis (anxiety reduction, IL-6 modulation, enkephalinase inhibition) while Semax addresses the neurotrophic axis (BDNF/NGF upregulation, TrkB sensitization). These are mechanistically distinct and complementary — Selank clears the neurochemical noise of chronic stress-driven HPA overactivation, while Semax rebuilds the neurotrophic support infrastructure. This pairing is the most commonly described cognitive protocol in the Russian pharmaceutical research literature and represents the combination with the greatest real-world clinical use outside the US.
Administration Note
Both agents share the intranasal route, so a physician managing this combination keeps them as separate nasal-spray devices rather than mixing them; specific dose and course length are individualized rather than fixed.
No pharmacokinetic interaction data exists for this pairing, but the two mechanisms are non-overlapping and combinatorial risk is considered low based on each compound's independent safety profile.
Semax upregulates BDNF and NGF at the gene expression level; Dihexa activates HGF/MET — a complementary receptor system whose downstream PI3K/Akt signaling overlaps with but is not identical to TrkB (BDNF receptor) signaling. The combination theoretically produces dual-receptor neurotrophic amplification: upstream BDNF production (Semax) combined with parallel MET-receptor synaptogenesis (Dihexa). Relevant for age-related cognitive decline where both neurotrophic factor levels and synaptic density are reduced.
Administration Note
Semax (intranasal) and Dihexa (oral) use different routes, which simplifies combining them logistically; specific dose and course length are physician-determined, and remain unestablished for Dihexa given the absence of any human dosing data.
Dihexa HGF/MET agonism raises the most significant theoretical safety concern in this combination: HGF/MET is an oncogenic pathway. Strict cancer history screen and LFT monitoring required before initiating. Do not combine in patients with any active or recent malignancy.
Selank + Semax + Dihexa
Full Cognitive Stack · All Three Axes
Rationale
The full three-compound stack addresses all three cognitive axes simultaneously: Selank (neuroimmune-adaptogen — HPA normalization, IL-6 modulation), Semax (neurotrophic axis — BDNF/NGF upregulation), and Dihexa (synaptogenesis axis — HGF/MET). Maximum theoretical coverage for complex cognitive decline presentations where anxiety, neurotrophic deficit, and synaptic loss are all contributing. This combination should be considered only after single-compound and two-compound trials have established tolerability and compound response in the individual patient.
Sequencing Recommendation
Step 1: Selank alone (4 weeks) → establish anxiolytic response and safety. Step 2: Add Semax (4 weeks) → assess neurotrophic/cognitive response. Step 3: Add Dihexa only if cancer screening is negative, LFTs baseline is normal, and clinical indication warrants the elevated-uncertainty compound.
Combining all three adds uncertainty proportionate to Dihexa's unknown human safety profile. Sequential introduction is strongly preferred over simultaneous initiation — it enables attribution of any adverse effect to a specific compound, which is clinically essential when one compound (Dihexa) has zero human safety data.
Evidence Appraisal
Evidence Quality Overview
Cognitive hub compounds exhibit the broadest evidence range of any hub on this platform — from EU-approved, Cochrane-reviewed compounds (Cerebrolysin) to purely preclinical rodent data with zero human pharmacokinetics (Dihexa). These ratings use a modified Oxford Centre for Evidence-Based Medicine hierarchy adapted for peptide research, where regulatory approval in any major jurisdiction counts as indirect evidence of human tolerability even absent Western RCT replication.
Cerebrolysin
Level IHighest-tier synthesis in this hub — and it is mixed, not favorable
Study Types
Multiple multi-country RCTs (Europe, Asia); 2023 Cochrane systematic review (Ziganshina et al., updating 2010/2020 versions); CARS-1/CARS-2 pooled analysis; CAPTAIN I & II TBI trials
Regulatory Basis
Approved EU, China, Korea, Philippines, Russia. Longest human safety record in this hub — decades of clinical use across multiple regulatory frameworks.
Key Caveat
FDA not approved. The 2023 Cochrane review's headline finding for acute ischemic stroke, across all severities, is no mortality benefit and roughly double the serious-adverse-event rate versus control — a real, reviewed finding, not a theoretical one. A narrower CARS-pooled subgroup (moderate-to-severe stroke) looks more favorable, but the two findings should always be cited together. Primary indication is acute stroke, TBI, and dementia — not healthy cognitive enhancement, which has no direct trial support.
Replication Status
Multi-country independent replication — strongest replication base in hub, with a genuinely mixed highest-tier result
Selank
Level IIbModerate certainty; single-country RCT base
Study Types
Russian RCTs with active comparators (vs. medazepam); open-label Phase II/III trials; mechanism studies (enkephalinase inhibition confirmed in vitro and in vivo)
Regulatory Basis
Russian Ministry of Health approved (generalized anxiety disorder). Published human data available for anxiolytic and anxio-nootropic indications.
Key Caveat
All pivotal trials conducted in Russia. English-language literature limited — translation and publication bias concern. No Western RCT replication. Small n in most trials.
Replication Status
Single-country (Russia) — no independent Western replication
Semax
Level IIbModerate certainty; stroke data strongest
Study Types
Russian Phase II/III RCTs in acute ischemic stroke (Gusev 1997 and subsequent); BDNF/NGF upregulation confirmed in human serum; mechanism studies published in English
Regulatory Basis
Russian Ministry of Health approved for ischemic stroke and TBI. Human safety data from Phase II/III stroke trials provides the most clinically relevant safety signal for this compound.
Key Caveat
Stroke approval ≠ validated nootropic use in healthy individuals. Nootropic dosing extrapolated from stroke data. Same single-country RCT limitation as Selank.
Replication Status
Single-country (Russia) — stroke indication only; nootropic use is off-protocol extrapolation
Pinealon
Level VPreclinical only
Study Types
Rodent and in vitro studies (Khavinson et al., St. Petersburg Institute of Bioregulation and Gerontology), plus one uncontrolled human cohort (Meshchaninov 2015, n=32) that combined Pinealon with a second peptide (Vesugen) — no randomized, blinded, or single-agent human trial exists. No controlled human trial identified.
Regulatory Basis
No regulatory approval in any jurisdiction for neurological indications. Research compound status.
Key Caveat
Human bioavailability, pharmacokinetics, and dose-response curves are entirely unknown. All proposed dosing is extrapolated from preclinical data. The "retinal ischemia" evidence sometimes attributed to Pinealon online actually belongs to Epithalon, a related but distinct Khavinson-family peptide.
Replication Status
Very limited publication base; primarily single research group
Dihexa
Level VHighest uncertainty in this hub
Study Types
Rodent behavioral studies (McCoy 2013 JPET; novel object recognition, spatial memory tasks). In vitro synaptogenesis assays. Zero published human pharmacokinetic, safety, or efficacy data.
Regulatory Basis
No approval in any jurisdiction. No IND-filed human trials identified. Research compound developed at Washington State University; not advanced to clinical development.
Key Caveat
HGF/MET pathway is an established oncogenic axis. The 10⁷× potency advantage vs. BDNF that makes Dihexa compelling in preclinical synaptogenesis assays is precisely what creates unknown carcinogenicity risk at sustained human doses. This is not theoretical — HGF/MET amplification drives multiple human cancers.
Replication Status
Preclinical replication in rodents only — no human data of any kind
Clinical Implication of This Hierarchy: The 4-tier evidence gap within this single hub has direct informed consent implications. A physician discussing Cerebrolysin can reference decades of multi-country human safety data and Cochrane-level systematic review. A physician discussing Dihexa must communicate that there are literally zero published human pharmacokinetic studies — not "limited" human data, but none at all. These conversations require fundamentally different informed consent frameworks, and any protocol that treats all five compounds as equivalent in evidence quality misrepresents the data. The compound selection and monitoring intensity recommendations throughout this hub are calibrated to this hierarchy.
Safety & Regulatory Reference
Safety & Regulatory Matrix
Cognitive hub compounds span a remarkable regulatory spectrum — from Russian pharma-approved compounds with clinical trial safety data (Selank, Semax, Cerebrolysin) to a compound with no human data whatsoever (Dihexa). Understanding where each compound sits in this spectrum is essential for appropriate informed consent and monitoring intensity decisions.
Compound
FDA Status
Other Approval
WADA Status
Key Safety Concern
Selank
No US Status / Not IND
Russian Pharma Approved — Anxiety Disorders
Not Listed (2025 prohibited list)
Drug interaction: enkephalinase inhibition prolongs opioid effect. No direct toxicity in clinical data.
Dihexa
No US Status / No IND / No Human Trials
No approval anywhere
Not Listed (mechanism not addressed)
HGF/MET oncogenic pathway activation — theoretical cancer promotion risk. Zero human PK or safety data. Highest uncertainty in this hub.
Semax
No US Status / Not IND
Russian Pharma Approved — Ischemic Stroke / TBI
Not Listed
ACTH-analogue: theoretical HPA suppression (mitigated by PGP extension). Mild vasopressor effect in some reports. Blood pressure monitoring advised.
Pinealon
No US Status / No IND
Research compound — limited availability
Not Listed
Extremely limited human safety data. Animal studies only for most indications. Handle as investigational.
Cerebrolysin
No US Status (imported for personal use only)
EU (Austria/Russia), China, South Korea, Latin America — dementia / stroke
Not Listed
IV/IM administration — requires medical setting. Infection risk at injection site. Porcine-derived — religious/ethical concern for some patients. Longest human-use history in this hub, but the 2023 Cochrane review found roughly double the serious-adverse-event rate vs. control in pooled stroke trials — discuss this alongside any benefit claim.
Note on Russian Regulatory Approvals: Selank and Semax both hold Russian Ministry of Health pharmaceutical approvals — a regulatory pathway different from the FDA's. Russian approval requires efficacy and safety data from controlled clinical trials, but the evidence standards, trial design, and peer-review requirements differ from FDA standards. These approvals represent meaningful evidence of clinical use safety, but should not be equated to FDA drug approval. The clinical trial data underpinning Russian approvals are largely published in Russian-language journals and have not been independently replicated in US or EU regulatory submissions.
Frequently Asked Questions
Cognitive Hub FAQ
How does Selank compare to benzodiazepines for anxiety?
Mechanism: Benzodiazepines bind GABA-A receptors directly and produce anxiolysis through chloride channel opening — an effect that creates physical tolerance within weeks and produces dependence. Selank inhibits enkephalinase (and related peptide-degrading enzymes), prolonging endogenous enkephalin activity without touching the GABA-A receptor. This mechanistic distinction is pharmacologically significant: no GABA-A tolerance mechanism, no withdrawal syndrome from the same pathway. What this does not mean: Selank is not a benzodiazepine-replacement for established anxiety disorders in clinical practice. Its evidence base is Russian-language, its regulatory approval is Russian, and it is not available through any US prescribing pathway. The distinction between Selank and benzodiazepines is scientifically meaningful — but Selank's own evidence base requires appropriate humility.
Why does Dihexa get special safety warnings when Selank and Semax have Russian approvals?
Human data, not regulatory status, drives safety assessment here. Selank and Semax have been administered to hundreds of patients in controlled clinical trials — their human safety profiles exist, even if the trials were conducted under Russian regulatory oversight. Dihexa has zero published human pharmacokinetic data and zero published human safety data. Extrapolating from rodent studies (10 mg/kg in rats) to human dosing introduces an uncertainty level that is qualitatively different from a Russian-approved compound with clinical trial data. Additionally, Dihexa's mechanism — HGF/MET receptor agonism — is a pathway with well-characterized oncogenic roles in carcinoma, which adds a specific theoretical safety concern absent for Selank and Semax. The safety warning differential is about evidence, not geography.
Can Semax be used after a stroke in the US? What are the realistic options?
Legal status: Semax is not FDA-approved, not on any IND, and not legally available from any US licensed pharmacy. It may be imported for personal use under FDA's personal use policy (typically a 90-day supply), though this is a gray area that the FDA can restrict. Clinical reality: No US physician can legally prescribe Semax — they can only document it as a patient-initiated supplement. In the context of stroke rehabilitation, the evidence most accessible to US physicians would be from the Russian trial publications (available in English in journals like Cerebrovascular Diseases) plus any published case reports. For patients who obtain Semax independently, the most important role a US physician can play is establishing baseline cognitive/neurological assessments, monitoring blood pressure, and confirming no contraindications — not prescribing the compound itself.
Does Selank actually improve memory, or is it only an anxiolytic?
The research data suggest Selank has two partially independent effects: anxiolytic (enkephalinase inhibition, GABAergic-adjacent but GABA-receptor-independent) and nootropic (BDNF mRNA upregulation in prefrontal cortex, serotonergic modulation). The practical question — does anxiolysis itself improve apparent cognitive performance, or is there a direct neurotrophic cognitive mechanism? — is difficult to separate in studies with anxious patients where anxiety is itself a cognitive impairment driver. The BDNF upregulation data (mRNA, not plasma protein) in the Russian publications adds mechanistic plausibility for a direct cognitive effect, but the magnitude of direct nootropic benefit independent of anxiety reduction is not clearly established. For practitioners: if the patient's cognitive complaint is secondary to anxiety and stress, Selank may address both simultaneously. If cognitive decline is the primary complaint with no anxiety component, Semax or Dihexa have more direct neurotrophic rationale.
What is the Selank/Semax combination used for in Russia?
In Russian clinical practice, Selank (anxiolytic-nootropic) and Semax (neuroprotective-nootropic) are used both as monotherapies and in combination. The combination is documented in cognitive enhancement research for treating asthenic and anxiety-driven cognitive decline, particularly in patients with post-infectious cognitive impairment (a clinical category more broadly used in Russian psychiatry than in US practice). The combination rationale — Selank normalizes the neuroimmune-HPA component while Semax rebuilds neurotrophic support — was developed at the Russian Institute of Molecular Genetics and is reflected in their prescribing recommendations. Neither compound is available in US pharmacies or through US prescribers under any current regulatory pathway.
Is there any risk of cognitive peptides making a cancer worse?
For Dihexa specifically, yes — the theoretical risk is significant and should be treated as a contraindication. HGF/MET (hepatocyte growth factor receptor) is an established oncogenic pathway. Activating MET signaling promotes tumor cell proliferation, migration, and invasion in carcinoma types where MET is amplified or overexpressed (gastric, lung, hepatic, renal). In the absence of human safety data specifically evaluating cancer outcomes with Dihexa, active malignancy or high-risk cancer history should be considered an absolute contraindication until human trial data exist. For Selank and Semax: No evidence in the Russian clinical trial literature links either compound to cancer promotion. Semax as an ACTH analogue does not stimulate pituitary-gonadal or pituitary-adrenal tumor growth through any established mechanism. Bottom line: Selank and Semax — low theoretical cancer concern; Dihexa — meaningful theoretical concern requiring active cancer exclusion before use.
General questions about the cognitive/nootropic peptide category as a whole — what this hub covers, how strong the evidence is, and how to think about safety and legality across the six compounds indexed here.
What cognitive peptides does PeptideReport.ai's Cognitive Research Hub cover?
This hub indexes six brain-focused peptides across three biological axes: Selank and Semax (Russian pharma-approved anxiolytic and neuroprotective peptides), Dihexa (a preclinical HGF/MET synaptogenesis compound), Cerebrolysin (an IV/IM neurotrophic peptide mixture with Cochrane-reviewed trial data), Pinealon (a preclinical Khavinson-lab tripeptide), and DSIP (an FDA Category 2 restricted sleep peptide with a thin evidence base). Rather than treating "cognitive peptides" as one uniform category, the hub organizes them by mechanism — neurotrophic, neuroimmune-adaptogen, and neuroprotective-vascular — because the evidence quality and clinical applicability differ sharply between compounds.
Are cognitive peptides like Selank and Semax FDA-approved?
No. None of the six compounds indexed in this hub carry FDA approval for any cognitive indication. Selank and Semax hold Russian Ministry of Health approval (for anxiety disorders and ischemic stroke/TBI, respectively), and Cerebrolysin is approved in the EU, China, and several other jurisdictions — but none of these approvals are equivalent to, or a substitute for, FDA clearance. Dihexa and Pinealon have no regulatory approval anywhere, and DSIP is an FDA Category 2 restricted substance with additional compounding-pharmacy restrictions.
How strong is the evidence behind cognitive peptides as a category?
Evidence quality varies more within this hub than in most categories — from Level I Cochrane-reviewed trial data (Cerebrolysin, though its headline acute-stroke finding is mixed rather than favorable) down to Level V preclinical-only data with zero human studies (Dihexa, Pinealon). Selank and Semax sit in between at Level IIb, supported by Russian-language RCTs that have not been independently replicated in Western literature. Because the category spans this entire hierarchy, no single evidence statement applies to "cognitive peptides" as a whole — each compound has to be evaluated on its own evidentiary merits.
What's the biggest safety consideration across the cognitive peptide category?
The category's central safety issue is the uneven human-data base described above: some compounds (Selank, Semax, Cerebrolysin) have documented human clinical-trial safety records, while others (Dihexa, Pinealon) have never been studied in humans at all. Dihexa carries an additional theoretical concern because its HGF/MET mechanism overlaps with a well-characterized oncogenic signaling pathway, and Cerebrolysin — despite its longer track record — showed roughly double the serious-adverse-event rate versus control in the 2023 Cochrane-reviewed stroke analysis. Any research interest in these compounds should be discussed with, and supervised by, a qualified physician.
How do I know which cognitive peptide might be relevant to my situation?
Relevance depends on which biological axis is in play — anxiety and neuroimmune dysregulation map to Selank's research profile, structural synaptic loss maps to Dihexa's (preclinical) mechanism, and post-stroke or post-TBI recovery aligns with Semax's clinical trial history. This hub's indication matrix and evidence-quality overview are built to help a physician connect a clinical picture to the relevant research, but the content here is educational only — it does not replace individualized evaluation by a treating physician.
Is it legal to research cognitive peptides such as Selank, Semax, or Dihexa in the US?
None of the six compounds in this hub are available through US-licensed pharmacies for cognitive indications, and DSIP additionally carries FDA Category 2 status, which further restricts compounding-pharmacy access. Legal status, importation rules, and research-chemical regulations vary by compound and change over time, so this page does not provide legal guidance — physicians and researchers should confirm current regulatory status independently, through appropriate legal and regulatory counsel, before pursuing any of these compounds.
Full Disclaimer
All content on this page is for research and educational purposes only. PeptideReport.ai does not provide medical advice, diagnosis, or treatment recommendations. No compound discussed on this page is FDA-approved for the indications described. Selank and Semax hold Russian Ministry of Health approval for specific indications — this does not constitute FDA approval and these compounds are not legally available through US-licensed pharmacies. Dihexa has no regulatory approval anywhere and has never been evaluated in a published human clinical trial. Cerebrolysin requires IV administration in a medical setting and is not available through US pharmacies. The information presented reflects published research and is provided for informational purposes only. Physicians interested in any of these compounds should conduct independent literature review and consult appropriate regulatory counsel before making clinical decisions. Patients should not self-administer any compound discussed here.
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Dr. Scott DelBoccio, DMD
Author · PeptideReport.ai · Research Content
Dr. DelBoccio is a dental medicine physician and researcher with a focus on peptide pharmacology and longevity medicine. PeptideReport.ai is a physician-authored E-E-A-T content platform providing research-grade information on peptide compounds for the medical and research communities. All hub and compound profile pages are authored by Dr. DelBoccio and reflect his independent synthesis of the primary literature.