Side-by-side · Research reference

P21vsSelank

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

AAnimal-MechanisticHUMAN-REVIEWED8/36 cited

BHuman-MechanisticAUTO-DRAFTED11/40 cited

P21

CNTF-Derived Neuropeptide · Animal Model Evidence

CNTFR/gp130Primary receptorGuo 2022

Animal onlyEvidence level

NeurogenesisPrimary effectJia 2020 Mottolese 2024

SQ · Site unspecified · Frequency unknown

Selank

Anxiolytic + Cognitive · Russian Pharma

150–300 mcg/doseIntranasalZaderej 2014

HumanMechanisticZaderej 2014 Medvedev 2007

~30 minOnset

Intranasal · 2–3×/day during stress / cognitive demand

01Mechanism of Action

Parameter

P21

Selank

Primary target

CNTF receptor alpha (CNTFRα) / LIF receptor (LIFR) / gp130 complex on neural stem cells

Monoamine system (serotonin / GABA modulation) + immunomodulation via tuftsin domainZaderej 2014

Pathway

CNTF mimetic → CNTFRα/LIFR/gp130 heterotrimer → JAK/STAT3 signaling → neurogenesis, stem cell proliferation, neuroprotection

Tuftsin-derived immune signaling + CNS monoamine modulation → reduced anxiety + improved mood / cognitionMedvedev 2007

Downstream effect

Increased neural stem cell self-renewal, globose basal cell activation (Mash1+ cells), olfactory sensory neuron regeneration, hippocampal neurogenesis, neuroprotection in developmental disorders

Anxiolytic + cognitive enhancement; immunomodulation via increased IL-6 + IFN-γMedvedev 2007 Zaderej 2014

Feedback intact?

—

No GABA-receptor binding; no dependence reportedMedvedev 2007

Origin

Small-molecule peptide mimetic derived from full-length ciliary neurotrophic factor (CNTF), designed to retain receptor activation with improved pharmacokineticsMottolese 2024

Synthetic 7-AA peptide derived from human tuftsin (immune-system tetrapeptide)Zaderej 2014

Antibody development

—

02Dosage Protocols

Parameter

P21

Selank

Human dosing

No established protocol

No clinical trial data available.

—

Animal models (mice)

Dose and route not specified in abstractsMottolese 2024 Jia 2020

In vitro and in vivo studies demonstrate efficacy; precise dosing protocols not disclosed.

—

Evidence basis

Animal models only

CDKL5 KO mice, methimazole-induced olfactory injury, CNTF-/- knockout models.Mottolese 2024 Cox 2026 Jia 2020

Human-mechanistic + Russian clinical trialsMedvedev 2007

Duration

Not specified

10–14 day cycles, repeated as needed

Route

Presumed subcutaneous or intraperitoneal (animal studies)

—

Standard dose

—

150–300 mcg / dose intranasalZaderej 2014

Frequency

—

2–3× per day during stress

Lower / starter dose

—

75 mcg / dose

Reconstitution

—

Pre-formulated nasal spray (commercial); research vial: bacteriostatic water

Timing

—

Morning + early afternoon preferred

Half-life

—

Short (minutes plasma); CNS effect lasts ~3 hr

04Side Effects & Safety

Parameter

P21

Selank

Human safety data

None available

No clinical trials in humans.

—

Animal tolerability

Well-tolerated in mouse models; no toxicity reported in available abstracts

—

Theoretical risks

Uncontrolled stem cell proliferation, immune response to peptide, unknown long-term CNS effects

—

Nasal irritation

—

Mild burning or congestion (transient)

Sedation

—

None — distinct from benzodiazepinesMedvedev 2007

Dependence / withdrawal

—

None reported in clinical useZaderej 2014

Cognitive impairment

—

None — opposite effect (enhancement)

Allergic reaction

—

Rare hypersensitivity

Long-term safety

—

Limited Western RCT data

Pregnancy / OB

—

Avoid — insufficient data

Absolute Contraindications

P21

·Use in humans not validated

Selank

·Pregnancy / breastfeeding
·Hypersensitivity to peptide

Relative Contraindications

P21

·Active malignancy (theoretical — neurotrophic signaling may affect tumour growth)
·Pregnancy or lactation (no safety data)

Selank

·Active autoimmune disease (theoretical via immunomodulation)

05Administration Protocol

Parameter

P21

Selank

1. Human protocol

Not established. No FDA approval, no clinical trial data.

Pre-formulated nasal spray (commercial) or research vial reconstituted with bacteriostatic water.

2. Animal research context

In vivo studies used systemic administration (route not specified in abstracts) in mouse models of neurodegeneration, olfactory injury, and CDKL5 deficiency disorder. In vitro studies used primary cell cultures.

Intranasal — 1–3 sprays per nostril per dose. Tilt head slightly back.

3. Timing

—

Morning + early afternoon for cognitive demand; PRN for acute anxiety.

4. Storage

—

Refrigerate after reconstitution; ≤30 days. Light-protected.

5. Caveat

—

Avoid co-administration with strong sedatives or other anxiolytics initially.