Peptide Comparison
P21 (P021)vsSelank
CNTF-derived neurotrophic tetrapeptide mimetic that promotes neurogenesis, enhances BDNF expression, and demonstrates disease-modifying potential in Alzheimer's models
A clever brain-boosting peptide derived from your immune system's natural tuftsin molecule—it calms anxiety and sharpens your mind without the drowsiness or addiction risks of traditional anti-anxiety medications.
At a Glance
Quick
comparison
Dose Range
P21 (P021)
500–1000 mcg
Selank
250–500 mcg
Frequency
P21 (P021)
Once daily
Selank
Once daily
Administration
P21 (P021)
Intranasal (spray)
Selank
Intranasal
Cycle Length
P21 (P021)
8-12 weeks
Selank
4-6 weeks
Onset Speed
P21 (P021)
Gradual (3-4 weeks)
Selank
Rapid (hours to days)
Evidence Level
P21 (P021)
Strong human trials (Phase 3 or FDA approved)
Selank
Limited human trials
Efficacy
Benefit
ratings
Cognitive
Anti-Aging
Healing & Recovery
Anxiety Relief
Cognitive Enhancement
Immune Support
Technical Data
Compound
specifications
P21 (P021)
Molecular Formula
C30H54N6O5
Molecular Weight
578.3 g/mol
Half-Life
>6 hours (for parent Peptide 6; P21 expected similar or improved due to adamantane modification)
Bioavailability
Orally bioavailable; BBB permeable (confirmed in preclinical studies)
CAS Number
Not assigned (research compound)
Selank
Molecular Formula
C33H57N11O9
Molecular Weight
751.9 g/mol
Half-Life
2-3 minutes (plasma); effects last hours due to downstream signaling
Bioavailability
High intranasal absorption; near 100% subcutaneous
CAS Number
129954-34-3
Protocols
Dosing
tiers
P21 (P021)
Selank
Applications
Best
suited for
P21 (P021)
Neurogenesis and Brain Cell Renewal
P21 was specifically designed to promote adult hippocampal neurogenesis — the birth of new neurons in the brain's primary memory center. Preclinical studies demonstrate robust increases in neuronal progenitor cell proliferation and maturation of newborn neurons into functional, synaptically connected cells in the dentate gyrus.
Alzheimer's Disease Research
P21 shows remarkable disease-modifying potential in 3xTg-AD Alzheimer's mice: reducing tau hyperphosphorylation, lowering soluble Aβ levels, rescuing synaptic deficits, and restoring cognitive function over 12-month treatment periods. Its mechanism targets the underlying pathology rather than just symptoms.
BDNF Enhancement
For individuals seeking to boost brain-derived neurotrophic factor levels, P21 provides a targeted approach through its inhibition of LIF signaling, leading to sustained BDNF upregulation. BDNF is critical for synaptic plasticity, memory formation, and neuronal survival.
Long-Term Neuroprotection
With demonstrated safety in animal studies up to 12 months of continuous treatment and without the adverse effects of native CNTF, P21 is suited for extended neuroprotective protocols aimed at maintaining cognitive function during aging.
Selank
Anxiety Without the Fog
If traditional anti-anxiety medications leave you feeling sedated, foggy, or 'not yourself,' Selank offers a refreshing alternative. It calms anxious thoughts while keeping your mind sharp—like turning down the volume on worry without muting your brain.
Cognitive Performers
Students, professionals, and anyone facing demanding mental tasks love Selank for its dual action. It simultaneously reduces performance anxiety while enhancing memory and focus—the best of both worlds when you need to think clearly under pressure.
Stress Resilience Seekers
Chronic stress wreaks havoc on your brain. Selank helps protect against stress-induced cognitive decline by supporting BDNF levels and modulating your stress response. Think of it as building a buffer between you and life's daily pressures.
Natural Approach Enthusiasts
Derived from tuftsin—a natural peptide your own immune system produces—Selank appeals to those seeking more 'natural' solutions. It works with your body's existing systems rather than overriding them like synthetic drugs.
Safety Profile
Side
effects
P21 (P021)
Common
- Nasal irritation (intranasal route)
- Mild headache
- Mild fatigue during adjustment
Uncommon
- Vivid dreams
- Mood fluctuations
Serious
- No serious adverse effects observed in preclinical studies
Selank
Common
- Nasal irritation
- Mild fatigue
- Mild headache
- Injection site redness
Uncommon
- Vivid dreams
- Dizziness
Serious
- Allergic reaction
Research Status
Safety
& evidence
P21 (P021)
Evidence Level
Strong human trials (Phase 3 or FDA approved)
FDA Status
Research compound
Safety Overview
P21 has demonstrated an excellent safety profile in preclinical animal studies, with up to 12 months of continuous treatment in mice showing no adverse effects. Critically, it does not produce the anorexia, hyperalgesia, and weight loss that limited clinical development of the parent molecule CNTF. The compound was specifically engineered to retain CNTF's neurotrophic benefits while eliminating its systemic side effects. No organ toxicity, tumorigenic effects, or behavioral abnormalities were reported in any published study.
Contraindications
- xKnown hypersensitivity to any component of the peptide formulation
- xPregnancy and breastfeeding — no reproductive safety data available
- xActive brain tumors or history of CNS malignancies — neurogenesis-promoting compounds may theoretically affect tumor growth
- xChildren and adolescents — effects on developing brains not studied
Selank
Evidence Level
Limited human trials
FDA Status
Research compound
Safety Overview
Selank has demonstrated a favorable safety profile across multiple Russian clinical studies spanning over two decades. In human trials comparing Selank to traditional anxiolytics like phenazepam, Selank showed comparable anti-anxiety effects with significantly better tolerability and no sedation, dependence, or memory impairment. The peptide has been approved for clinical use in Russia since the 1990s for anxiety and neurasthenia.
Contraindications
- xPregnancy or planning to become pregnant
- xCurrently breastfeeding
- xKnown allergy to peptide components
- xChildren and adolescents
- xSevere psychiatric disorders requiring immediate intervention
Decision Guide
Which is
right for you?
Choose P21 (P021) if...
- Supporting neurogenesis and brain cell renewal in age-related cognitive decline
- Enhancing learning capacity and memory consolidation
- Neuroprotection through BDNF upregulation and tau pathology reduction
- Research into disease-modifying Alzheimer's disease therapies
Choose Selank if...
- Anxiety relief without sedation
- Cognitive enhancement and focus
- Memory improvement
- Stress resilience