Peptides for Brain Health: Compounds Studied for Cognitive Function

Key Takeaways

• Compounds covered: Cerebrolysin, semax, selank, dihexa, P21/P021, BPC-157
• Goal area: Neuroprotection, cognitive function support, neurogenesis, neuroinflammation reduction
• Evidence range: Ranges from multiple completed human trials in Alzheimer's and stroke (cerebrolysin) to animal-only preclinical data (dihexa, P21, BPC-157 for CNS); no compound in this group is FDA-approved for cognitive function
• Regulatory range: Includes substances that some US compounding pharmacies compound despite absence from FDA's Category 1 list (cerebrolysin, semax, selank), a substance outside any FDA-permissible compounding category (BPC-157, removed from Category 2 on April 22, 2026), and research reagents not approved for human use (dihexa, P21).
• Key biomarkers for brain health: IGF-1 (neurotrophic context), TSH (thyroid dysfunction causes cognitive symptoms), B12 (reversible deficiency cause), hs-CRP (neuroinflammation), fasting glucose/HbA1c (insulin resistance and cognitive function)
• As of April 22, 2026: No peptide in this article is FDA-approved for cognitive function enhancement or neuroprotection. Some US compounding pharmacies compound cerebrolysin, semax, and selank, though these substances do not appear on FDA's Category 1 bulk drug substances list and lack US monographs; the legal basis for compounding is uncertain. BPC-157 was removed from the FDA Category 2 list on April 22, 2026 and is outside any FDA-permissible compounding category. Dihexa and P21 are research reagents with no prescribing pathway.
• Bottom line: Among the compounds profiled in this article, cerebrolysin has the most completed human clinical trial data (for Alzheimer's disease and post-stroke cognitive impairment); none of the profiled compounds is FDA-approved for any cognitive indication in the US, and the 503A compounding basis for cerebrolysin, semax, and selank — all foreign-approved but not on FDA's Category 1 list and lacking US monographs — is regulatorily uncertain.

Understanding Brain Health: The Biology

Cognitive function depends on the integrity of several overlapping biological systems: neuronal survival and structural maintenance, synaptic density and plasticity, cerebrovascular supply, glymphatic clearance of metabolic waste (primarily during slow-wave sleep), and the suppression of neuroinflammatory cascades that, when chronic, accelerate neurodegeneration.

Peptides are structurally suited to interact with these systems for several reasons. Their relatively small molecular size — compared to proteins — facilitates passage across or interaction with the blood-brain barrier. Their receptor selectivity allows targeted engagement with neurotrophic factor pathways, neurotransmitter systems, and inflammatory signaling cascades. And their endogenous origin in many cases (semax is derived from ACTH; cerebrolysin contains fragments of naturally occurring neurotrophins) provides mechanistic grounding for their proposed activity in CNS pathways.

The neurotrophins — BDNF, NGF, CNTF, and related growth factors — are among the most studied targets in neuropeptide research. BDNF in particular regulates neuronal survival, dendritic growth, and long-term potentiation (the synaptic strengthening mechanism underlying memory formation). A key vulnerability in aging and neurodegeneration is the decline of BDNF signaling in the hippocampus and prefrontal cortex — the regions most associated with memory and executive function.

Neuroinflammation represents the other major mechanistic axis. Activated microglia and astrocytes produce inflammatory cytokines (IL-1beta, TNF-alpha, IL-6) that, when chronically elevated, impair synaptic transmission and accelerate amyloid and tau pathology in Alzheimer's-relevant contexts. Multiple compounds in this article are studied in part for their anti-inflammatory and neuroprotective effects on this pathway. Systemic inflammation, as measured by hs-CRP, provides a peripheral proxy for this neuroinflammatory burden that is assessable through standard bloodwork.

Peptides Studied for Brain Health: A Quick Comparison

The following peptides have published evidence relevant to cognitive function or neuroprotection. They are listed by strength of clinical evidence, from most-studied to least.

• Compound: Cerebrolysin
  Mechanism for brain health: Neurotrophic factor mixture (BDNF, NGF, CNTF fragments); neuroprotection, reduced amyloid pathology, neurogenesis support in Alzheimer's models
  Evidence: Multiple completed human trials in Alzheimer's disease and post-stroke cognitive impairment; foreign regulatory approvals (Germany, Austria, Russia, China) that do not confer US regulatory status; no FDA approval
  FDA status: Not FDA-approved; does not appear on FDA's Category 1 list of bulk drug substances for 503A compounding and lacks a US monograph; some US compounding pharmacies nonetheless compound cerebrolysin or cerebrolysin-like preparations, on a tenuous legal basis
  SP availability: Not currently offered through Superpower
  Route: Intravenous or intramuscular injection where compounded (provider- and pharmacy-determined; regulatorily uncertain basis as discussed in the regulatory section below)
• Compound: Semax
  Mechanism for brain health: BDNF upregulation in hippocampus and basal forebrain; neuroprotection under ischemia; modulation of default mode network connectivity
  Evidence: Animal studies; neuroimaging studies in humans; Russian clinical approvals for ischemic stroke (foreign approvals do not confer US regulatory status); no Phase 3 Western RCT
  FDA status: Not FDA-approved; does not appear on FDA's Category 1 list of bulk drug substances for 503A compounding and lacks a US monograph; some US compounding pharmacies compound semax, on a tenuous legal basis
  SP availability: Not currently offered through Superpower
  Route: Nasal spray or subcutaneous injection where compounded (provider- and pharmacy-determined; regulatorily uncertain basis as discussed in the regulatory section below)
• Compound: Selank
  Mechanism for brain health: Anxiolytic and cognitive-modulatory effects through GABA-benzodiazepine-adjacent mechanisms; whole-brain connectivity modulation documented in neuroimaging
  Evidence: Human studies conducted in Russia (foreign approvals do not confer US regulatory status); neuroimaging data; no independent Phase 3 Western RCT
  FDA status: Not FDA-approved; does not appear on FDA's Category 1 list of bulk drug substances for 503A compounding and lacks a US monograph; some US compounding pharmacies compound selank, on a tenuous legal basis
  SP availability: Not currently offered through Superpower
  Route: Nasal spray or subcutaneous injection where compounded (provider- and pharmacy-determined; regulatorily uncertain basis as discussed in the regulatory section below)
• Compound: BPC-157
  Mechanism for brain health: Proposed indirect CNS effects via gut-brain axis (animal models only); no established mechanism in humans; no human cognitive trial data
  Evidence: Animal studies for CNS effects; no human cognitive trial data
  FDA status: Not FDA-approved; removed from FDA Category 2 list on April 22, 2026; outside any FDA-permissible compounding category
  SP availability: Not currently available through Superpower
  Route: Research use only; no legal human administration pathway under current US regulatory status
• Compound: Dihexa
  Mechanism for brain health: Hepatocyte growth factor/c-Met agonist; synaptogenesis; cognitive rescue in Alzheimer's animal models
  Evidence: Animal studies and in vitro data only; no human clinical trial data
  FDA status: Research-only; not approved for human use anywhere
  SP availability: Not available through Superpower or any licensed prescriber
  Route: Research use only
• Compound: P21 / P021
  Mechanism for brain health: CNTF-derived tetrapeptide; promotes hippocampal neurogenesis, synaptic density, spatial memory; tau reduction in Alzheimer's animal models
  Evidence: Animal studies only; no human clinical trial data
  FDA status: Research-only; not approved for human use anywhere
  SP availability: Not available through Superpower or any licensed prescriber
  Route: Research use only

Compounds listed as "research-only" have not completed the clinical trial process required for FDA approval. They are not legal to prescribe or sell for human use in the US. Their inclusion here is for educational context only.

Peptides Studied for Brain Health: Individual Profiles

Each compound below targets cognitive function through distinct mechanisms. A provider evaluating neuropeptide options would consider the specific cognitive concern — neuroprotection in neurodegeneration, anxiety-adjacent cognitive impairment, recovery from injury, or general neuroplasticity support — along with the evidence quality and regulatory access before any compound is discussed.

Cerebrolysin

Cerebrolysin is a standardized mixture of neurotrophic factor peptides derived from porcine brain tissue through enzymatic digestion. Its active components include low-molecular-weight fragments of BDNF, NGF, CNTF, and other neurotrophins. The proposed mechanism involves multiple neuroprotective pathways: enhancing neuronal survival, reducing amyloid precursor protein processing, supporting neurogenesis, and decreasing neuroinflammatory activity.

As a porcine-brain-derived biologic, cerebrolysin sits outside the typical scope of US 503A compounding, which is not designed for animal-tissue-sourced multi-peptide biologics. API sourcing, TSE safety documentation, and quality control standards for any compounded cerebrolysin preparation would be at the compounding pharmacy's discretion and are not standardized in the US.

A 2009 comprehensive review by Plosker and colleagues in Drugs & Aging covered cerebrolysin's clinical trial evidence in Alzheimer's disease, including multiple randomized controlled trials showing cognitive improvement on ADAS-cog and other standardized measures. A 2003 study by Rockenstein and colleagues in the Journal of Neural Transmission reported neuroprotective effects in a transgenic Alzheimer's mouse model, including behavior and amyloid pathology outcomes in the model — a primary mechanistic citation for cerebrolysin's proposed neuroprotective activity. A 2015 study by Rockenstein and colleagues in Stem Cell Research showed cerebrolysin improves neural stem cell graft survival in an APP transgenic model, adding a neurogenesis dimension. A 2015 study by Zhang and colleagues in the Journal of Neurosurgery demonstrated improved cognitive performance after mild TBI in rats, partly through reduced astrogliosis and increased neurogenesis. A 2024 comparison by Seidl and colleagues in the Journal of Medicine and Life compared cerebrolysin's biological activity and composition with other peptide preparations. [Multiple human RCTs for Alzheimer's; Phase II/III depending on indication and country]

A 2000 study by Alvarez and colleagues in Journal of Neural Transmission. Supplementum reported oral cerebrolysin effects on brain alpha activity and cognitive measures in elderly controls — the only available human cognitive-enhancement data; this study requires careful interpretation given its design limitations.

As of April 2026, cerebrolysin is not FDA-approved for any indication. It carries regulatory approvals for Alzheimer's disease and post-stroke rehabilitation in Germany, Austria, Russia, and China; these foreign approvals do not confer US regulatory status, and cerebrolysin remains not FDA-approved. Some US compounding pharmacies compound cerebrolysin or cerebrolysin-like preparations despite its absence from FDA's Category 1 list and the lack of a US monograph; the legal basis for compounding is therefore uncertain. Cerebrolysin is not currently offered through Superpower.

Semax

Semax is a synthetic heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro) derived from a fragment of ACTH that retains neurotrophic activity without ACTH's hormonal effects on cortisol or adrenal function. It was developed at the Institute of Molecular Genetics in Moscow.

Its cognitive mechanism centers on BDNF. A 2006 study by Dolotov and colleagues in Brain Research reported that semax modulates BDNF and TrkB expression in rat hippocampus — the primary mechanistic citation for semax's cognitive effects. A companion 2006 study by the same group in the Journal of Neurochemistry showed semax increases BDNF protein levels in rat basal forebrain. An earlier 2003 study by Dolotov and colleagues in Doklady Biological Sciences showed semax stimulates BDNF expression in multiple rat brain areas in vivo, characterizing the cellular mechanism. In an ischemic context, a 2006 study by Romanova and colleagues in the Bulletin of Experimental Biology and Medicine reported neuroprotective and memory-preserving effects of semax in a model of experimental ischemic cortical infarction. [Animal study / In vitro; Russian clinical data for stroke]

Neuroimaging evidence: a 2018 study by Lebedeva and colleagues in Bulletin of Experimental Biology and Medicine reported effects of semax on the default mode network — functional connectivity changes observable on resting-state fMRI. A 2020 study by Panikratova and colleagues in Doklady Biological Sciences examined selank and semax effects on whole-brain resting-state connectivity.

Semax carries a Russian approval for ischemic stroke and cognitive impairment following ischemia; foreign approvals do not confer US regulatory status. It is not FDA-approved. Semax does not appear on FDA's Category 1 list of bulk drug substances for 503A compounding and lacks a US monograph; some US compounding pharmacies nonetheless compound semax as a nasal spray or injectable, on a regulatorily uncertain basis. FDA has issued warning letters to compounders marketing foreign-approved non-Category-1 peptides for human use; enforcement posture on semax specifically can change without notice. The use of semax for cognitive enhancement in non-stroke contexts has not been approved by the FDA; its safety and efficacy for this use have not been established through adequate and well-controlled clinical trials in Western populations.

Selank

Selank is a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) developed at the Institute of Molecular Genetics in Moscow as an anxiolytic with proposed cognitive-modulatory effects. It is structurally derived from tuftsin, an immunomodulatory tetrapeptide. Its proposed mechanism involves GABAergic and serotonergic systems, with proposed anxiolytic activity that may secondarily improve cognitive performance in anxiety-impaired subjects.

A 2018 review by Vyunova and colleagues in Protein and Peptide Letters reviewed the molecular aspects of selank's biological activity as a peptide-based anxiolytic — the primary mechanistic citation. The 2020 functional connectomics study by Panikratova and colleagues in Doklady Biological Sciences examined combined selank and semax effects on brain connectivity, providing neuroimaging context for selank's CNS activity. [Human studies conducted in Russia; neuroimaging data; no independent Phase 3 Western RCT]

Selank carries a Russian approval as an anxiolytic; foreign approvals do not confer US regulatory status. Selank is not FDA-approved for any indication; its use for cognitive enhancement or anxiety has not been established through adequate and well-controlled clinical trials in the US. Selank does not appear on FDA's Category 1 list of bulk drug substances for 503A compounding and lacks a US monograph; some US compounding pharmacies nonetheless compound selank, on a regulatorily uncertain basis. FDA has issued warning letters to compounders marketing foreign-approved non-Category-1 peptides for human use; enforcement posture on selank specifically can change without notice. Not currently offered through Superpower.

BPC-157

BPC-157 has been studied in animal models for proposed indirect CNS effects via the gut-brain axis. A 2022 review by Vukojevic and colleagues in Neural Regeneration Research summarized preclinical BPC-157 CNS-related findings in animal models. A 2016 review by Sikiric and colleagues in Current Neuropharmacology summarized BPC-157 preclinical brain-gut axis findings. A 2025 review by Jozwiak and colleagues in Pharmaceuticals summarized BPC-157 preclinical pharmacology across multiple tissues. None of these reviews establish human efficacy, safety, or dose for any CNS indication; BPC-157 has no completed human cognitive trial data and no FDA-approved indication. [Animal study; no human cognitive trial data]

BPC-157 is not FDA-approved for any indication. As of April 22, 2026, FDA removed BPC-157 from the Category 2 list of bulk drug substances under 503A/503B consideration. Removal is not equivalent to Category 1 approval; it places BPC-157 outside any FDA-permissible compounding category. BPC-157 is not eligible for 503A compounding and is not legally available through US licensed prescribers. PCAC review remains pending separately. BPC-157 is not currently available through Superpower.

Dihexa

Dihexa is a synthetic angiotensin IV analog (N-hexanoic-Tyr-Ile-(6) aminohexanoic amide) developed at Washington State University as a small-molecule drug candidate with peptide-like receptor activity. It is a hepatocyte growth factor (HGF)/c-Met system agonist with proposed synaptogenesis activity in the hippocampus.

A 2014 study by Benoist and colleagues in the Journal of Pharmacology and Experimental Therapeutics reported that dihexa's preclinical procognitive and synaptogenic activity depends on HGF/c-Met system activation — the primary mechanistic citation. A 2021 study by Sun and colleagues in Brain Sciences reported dihexa reversed cognitive deficits in APP/PS1 Alzheimer's mice via the PI3K/AKT pathway. A 2015 review by Wright and colleagues in Progress in Neurobiology reviewed the development of small-molecule angiotensin IV analogs including dihexa as candidates for Alzheimer's and Parkinson's disease contexts. [Animal study / In vitro only; no human clinical trial data]

This compound has not been approved by the FDA for any medical use. Dihexa has not entered any Investigational New Drug (IND) program with FDA; it is a research reagent, not a clinical drug candidate with an active regulatory pathway. Research is limited to laboratory and animal studies; no human clinical trial data has been published. Dihexa is not available through Superpower or any licensed prescriber for any use. Its appearance in this article is limited to summarizing publicly available preclinical literature.

P21 / P021

P021 (also written P21) is a synthetic tetrapeptide (Ac-DGGLAG-NH2) derived from ciliary neurotrophic factor (CNTF), designed to penetrate the blood-brain barrier and activate STAT3 and related neurogenic pathways without CNTF's systemic inflammatory liability. Its proposed mechanism centers on hippocampal neurogenesis and synaptic maintenance.

A 2010 study by Blanchard and colleagues in the Journal of Alzheimer's Disease reported that the CNTF tetrapeptide scaffold enhanced adult hippocampal neurogenesis, plasticity, and spatial memory measures in animal models — the primary citation for the P21 neurogenesis mechanism. A 2017 study by Baazaoui and colleagues in Alzheimer's Research & Therapy reported P021 reduced dendritic and synaptic deficits and cognitive impairment in Alzheimer's animal models. A 2021 study by Wei and colleagues in the Journal of Alzheimer's Disease reported P021 reduced Alzheimer-like behavior and synaptic dysfunction in animal models when initiated in early development. [Animal study / In vitro only; no human clinical trial data]

This compound has not been approved by the FDA for any medical use. P21 has not entered any Investigational New Drug (IND) program with FDA; it is a research reagent, not a clinical drug candidate with an active regulatory pathway. Research is limited to animal and in vitro studies. P21 is not available through Superpower or any licensed prescriber. Its appearance in this article is limited to summarizing publicly available preclinical literature.

Regulatory Status at a Glance

As of April 2026, the peptides discussed in this article carry the following regulatory statuses. These distinctions matter when discussing any of them with a healthcare provider.

• Cerebrolysin: Not FDA-approved for any indication; carries foreign approvals in multiple European and Asian countries that do not confer US regulatory status; does not appear on FDA's Category 1 list of bulk drug substances for 503A compounding and lacks a US monograph. Some US compounding pharmacies compound cerebrolysin on a tenuous legal basis.
• Semax: Not FDA-approved; carries a Russian approval for ischemic stroke that does not confer US regulatory status; does not appear on FDA's Category 1 list and lacks a US monograph. Some US compounding pharmacies compound semax on a tenuous legal basis.
• Selank: Not FDA-approved; carries a Russian approval as an anxiolytic that does not confer US regulatory status; does not appear on FDA's Category 1 list and lacks a US monograph. Some US compounding pharmacies compound selank on a tenuous legal basis.
• BPC-157: Not FDA-approved for any indication; removed from FDA Category 2 list on April 22, 2026; outside any FDA-permissible compounding category; not eligible for 503A compounding and not legally available through US prescribers. PCAC review remains pending separately.
• Dihexa: Research reagent; has not entered an IND program; not approved for human use anywhere; not available by prescription in the US.
• P21 / P021: Research reagent; has not entered an IND program; not approved for human use anywhere; not available by prescription in the US.

Compounds listed as "research-only" are not legal to prescribe, compound, or sell for human use in the US. Their presence in this article is for educational context only. A 2026 review by Mendias and colleagues in Sports Medicine reviewed safety and efficacy evidence for approved and unapproved peptide therapies, emphasizing the evidentiary gap between preclinical and clinical data for most compounds in this category.

Considerations When Comparing Peptides for Brain Health

Direct comparison between these compounds is not supported by the evidence. They have been studied in different populations, using different endpoints, in different countries, and at different stages of clinical development. Inferring relative effectiveness from separate trials is methodologically unreliable.

What is the specific cognitive concern: Neuroprotection in the context of Alzheimer's-relevant pathology (cerebrolysin, P21), recovery from acute ischemic injury (semax, cerebrolysin), anxiety-adjacent cognitive impairment (selank), synaptogenesis for memory loss (dihexa), or general neuroplasticity support each implicate different mechanisms. The appropriate compound — if any — depends on the specific biological problem being addressed.

Evidence level: Cerebrolysin is the only compound in this group with multiple completed human RCTs for cognitive indications. Semax and selank have human data but from non-independent Russian clinical contexts without Western replication. Dihexa and P21 have animal-only data. BPC-157's brain relevance is based on indirect mechanisms. A provider will factor in evidence quality as a primary consideration.

What biomarkers show before starting: Multiple systemic conditions cause cognitive symptoms that are addressable without any neuropeptide — thyroid dysfunction, B12 deficiency, insulin resistance, and chronic inflammation are all identifiable and correctable through standard bloodwork. A baseline panel should precede any neuropeptide discussion to ensure reversible causes have been excluded.

Regulatory status and access: Cerebrolysin, semax, and selank may be compounded by some US pharmacies, though they do not appear on FDA's Category 1 list and the legal basis for compounding is uncertain. BPC-157 was removed from the FDA Category 2 list on April 22, 2026 and is outside any FDA-permissible compounding category. Dihexa and P21 have no legal pathway to human use. These differences are material to any clinical conversation.

A licensed provider will evaluate the full clinical picture — including health history, current medications, existing neurological or psychiatric conditions, and baseline lab values — before considering any compound in this category.

Safety Considerations

Side effects vary significantly by compound and individual response. No blanket safety statement applies to brain health peptides.

Cerebrolysin has the most clinical safety data, derived from multiple completed trials. Adverse effects documented in clinical studies include injection-site reactions, GI symptoms, and infrequent CNS-related effects. As a porcine-derived preparation, allergic reactions are possible. Semax and selank have been administered to human subjects in Russian clinical contexts; systematic adverse event profiles from independently conducted trials are not available in Western literature. Dihexa and P21 have no human safety data at any dose. BPC-157's human safety data is limited and does not include cognitive use cases.

Contraindications that apply broadly to brain health peptide therapy include:

• Active seizure disorder: compounds with CNS-activating mechanisms require careful evaluation in this context
• Active psychiatric medications: compounds with proposed effects on serotonin, dopamine, and GABAergic systems (selank, BPC-157) carry theoretical potential for pharmacological interaction with antidepressants, antipsychotics, and anxiolytics
• Pregnancy and breastfeeding: reproductive safety data does not exist for any compound in this group
• Active or history of CNS malignancy: neurotrophic growth factor activity (cerebrolysin, semax BDNF effects) requires careful evaluation in neoplastic CNS contexts
• Sourcing from unregulated vendors: products sold outside licensed pharmacy channels carry contamination, dosing, and misidentification risks

For compound-specific side effect profiles, see individual compound pages and consult a licensed provider.

What to Test Before Starting Peptides for Brain Health

Baseline biomarker testing for brain health serves two distinct purposes: identifying reversible, systemic causes of cognitive symptoms before any neuropeptide is considered, and establishing safety baselines for any injectable compound.

• IGF-1: Growth hormone-related neurotrophic activity declines with age and is associated with reduced hippocampal neurogenesis. A baseline IGF-1 level characterizes GH-axis neurotrophic context and is directly relevant for cerebrolysin and semax, which interact with neurotrophic growth factor pathways.
• TSH and thyroid panel: Thyroid dysfunction — both hypothyroidism and hyperthyroidism — is associated with cognitive symptoms including memory impairment, brain fog, and processing speed reduction; these symptoms often improve with appropriate thyroid management. Baseline TSH rules out thyroid dysfunction before attributing cognitive symptoms to neurodegeneration.
• Vitamin B12: B12 deficiency can cause reversible cognitive impairment through its role in myelin synthesis and homocysteine metabolism. It is common in older adults and in those using metformin or acid-suppressive medications. Testing vitamin B12 identifies a correctable cause before any peptide therapy is considered.
• hs-CRP: Neuroinflammation is associated with cognitive decline and is partially reflected in peripheral inflammation markers. Elevated hs-CRP signals chronic low-grade inflammation that may be independently impairing cognitive function — and that multiple compounds in this article are proposed to address through anti-inflammatory mechanisms.
• Fasting glucose and HbA1c: Insulin resistance is associated with cognitive impairment through proposed mechanisms including reduced cerebral glucose uptake, increased oxidative stress, and disrupted hippocampal neurogenesis. Baseline fasting glucose and HbA1c characterize the metabolic context that affects brain health independently of any peptide.
• Homocysteine: Elevated homocysteine is independently associated with cognitive decline and white matter damage. Homocysteine levels respond to B12, folate, and B6 repletion; whether B-vitamin-driven homocysteine lowering independently improves cognitive outcomes remains debated in the clinical literature. A homocysteine measurement alongside B12 characterizes the full one-carbon metabolism picture.
• Comprehensive metabolic panel: Liver and kidney function baselines are safety prerequisites for any injectable compound. ALT, AST, creatinine, and BUN establish organ function context before starting any parenteral peptide.

The neurotransmitter and cognitive longevity biomarker guide covers the full set of markers relevant to brain health. IGF-1, TSH, B12, and hs-CRP together identify the four most common systemic drivers of cognitive symptoms that are reversible without any neuropeptide — making this panel the most consequential baseline for anyone evaluating cognitive decline or function optimization.

How to Access These Peptides Safely

Some US compounding pharmacies compound cerebrolysin, semax, and selank for prescribing providers, though these substances do not appear on FDA's Category 1 list of bulk drug substances for 503A compounding and lack US monographs; the legal basis for compounding is uncertain and FDA has issued warning letters to compounders of foreign-approved non-Category-1 peptides. Availability through any specific US prescriber is not guaranteed and depends on the compounding pharmacy's own regulatory analysis. BPC-157 was removed from the FDA Category 2 list on April 22, 2026 and is outside any FDA-permissible compounding category. Dihexa and P21 have no legal path to human use in the US.

A provider evaluation for brain health peptide considerations typically involves a neurological or cognitive symptom assessment, relevant lab work (IGF-1, TSH, B12, hs-CRP, metabolic panel, homocysteine), review of neuroimaging if available, and a complete medication review. This evaluation establishes whether a peptide compound is appropriate, and — critically — whether systemic causes of cognitive symptoms have been excluded first.

Self-directed use of injectable neuropeptides without provider involvement creates risks specific to this category: these compounds have proposed effects on neurotransmitter and neurotrophic pathways (serotonin, dopamine, GABA, BDNF), and may have complex interactions with psychiatric medications, blood-pressure medications, and anticoagulants. Products sold through unregulated online channels as any of the peptides discussed in this article (including BPC-157, dihexa, P21, cerebrolysin, semax, or selank) have not been evaluated by the FDA for identity, purity, or potency. FDA has issued warnings about contaminated and counterfeit "research peptide" products. The research-only label on such products does not confer a legal basis for human use.

Understanding Your Baseline

The brain health peptide category illustrates a consistent pattern in this space: mechanistic evidence in animal models and preliminary human studies precedes — sometimes by decades — the Phase 3 trial data needed to confirm clinical efficacy. Cerebrolysin is the closest to validated, and it still lacks FDA approval. Dihexa and P21 have compelling animal data that has not yet been tested in a single human trial.

In that gap, baseline biomarker data does the most durable work. Identifying thyroid dysfunction, B12 deficiency, insulin resistance, or chronic inflammation as contributors to cognitive symptoms is both evidence-based and immediately actionable — with or without any peptide compound. That is the baseline that makes any subsequent clinical decision, including a conversation about neuropeptides, more precise and more purposeful.

That principle — test first, then decide — is central to Superpower's approach to preventive health. Whether the conversation with a provider leads to a compounded neuropeptide, an optimization of metabolic and nutritional markers, or a referral for neurological evaluation, the starting point is the same: knowing what your biology shows before selecting any intervention.

IMPORTANT SAFETY INFORMATION

Cerebrolysin is not approved by the FDA for any indication. Foreign approvals in European and Asian countries do not confer US regulatory status. Cerebrolysin does not appear on FDA's Category 1 list of bulk drug substances for 503A compounding and lacks a US monograph; compounded cerebrolysin is not an FDA-approved product and the legal basis for compounding is uncertain. As a porcine-brain-derived biologic, allergic reactions are possible and TSE/BSE safety documentation is at the compounding pharmacy's discretion. Contraindications include active CNS neoplasm, known hypersensitivity, pregnancy or breastfeeding (reproductive safety not established), active seizure disorder (CNS activation risk). Common adverse effects in clinical studies: injection-site reactions, GI symptoms, headache. Long-term safety data from Phase 3 US trials does not exist. Cerebrolysin is not currently offered through Superpower.

Semax is not FDA-approved for any indication. Foreign approvals (Russia) do not confer US regulatory status. Semax does not appear on FDA's Category 1 list of bulk drug substances for 503A compounding and lacks a US monograph; some US compounding pharmacies nonetheless compound semax as a nasal spray or injectable, on a tenuous legal basis. The use of semax for any indication has not been approved by the FDA; its safety and efficacy for cognitive enhancement or neuroprotection have not been established through adequate and well-controlled clinical trials in Western populations. Contraindications include pregnancy, breastfeeding, active seizure disorder, and concurrent use of serotonergic medications (potential interaction). Not currently offered through Superpower.

Selank is not FDA-approved for any indication. Foreign approvals (Russia) do not confer US regulatory status. Selank does not appear on FDA's Category 1 list of bulk drug substances for 503A compounding and lacks a US monograph; some US compounding pharmacies nonetheless compound selank, on a tenuous legal basis. Its safety and efficacy have not been established through FDA-reviewed clinical trials. Selank has proposed GABAergic and serotonergic mechanisms that may interact with CNS-active medications including benzodiazepines and antidepressants. Contraindications include pregnancy, breastfeeding, and concurrent CNS-active medication use without provider supervision. Not currently offered through Superpower.

BPC-157 is not approved by the FDA for any medical use. As of April 22, 2026, FDA removed BPC-157 from the Category 2 list of bulk drug substances under 503A/503B consideration. Removal is not equivalent to Category 1 approval; BPC-157 is outside any FDA-permissible compounding category, is not eligible for 503A compounding, and is not legally available through US licensed prescribers. PCAC review remains pending separately. BPC-157 is not currently prescribed, compounded, or dispensed through Superpower. This information is provided for educational purposes only.

Dihexa is not approved by the FDA for any medical use. Dihexa has not entered any Investigational New Drug (IND) program with FDA; it is a research reagent, not a clinical drug candidate. Research has been limited to laboratory and animal studies. Its safety, efficacy, appropriate dosing, and long-term effects in humans have not been established. Dihexa is not prescribed, compounded, or dispensed through Superpower or any licensed prescriber. This information is provided for educational purposes only.

P21 / P021 is not approved by the FDA for any medical use. P21 has not entered any Investigational New Drug (IND) program with FDA; it is a research reagent, not a clinical drug candidate. Research has been limited to animal and in vitro studies. Its safety, efficacy, appropriate dosing, and long-term effects in humans have not been established. P21 is not prescribed, compounded, or dispensed through Superpower or any licensed prescriber. This information is provided for educational purposes only.

Full FDA-approved prescribing information at dailymed.nlm.nih.gov.

Disclaimer: This article discusses multiple peptide compounds with different regulatory statuses. Some are available through compounding pharmacies; others are not approved for human use. None of the compounds discussed in this article are currently offered, prescribed, compounded, or dispensed through Superpower. This educational content is editorially independent.