Peptide Comparison
P21 (P021)vsSemax
CNTF-derived neurotrophic tetrapeptide mimetic that promotes neurogenesis, enhances BDNF expression, and demonstrates disease-modifying potential in Alzheimer's models
A brain-boosting peptide that supercharges your cognitive function by ramping up BDNF—the protein your neurons need to grow, connect, and stay sharp—all delivered through a simple nasal spray.
At a Glance
Quick
comparison
Dose Range
P21 (P021)
500–1000 mcg
Semax
200–900 mcg
Frequency
P21 (P021)
Once daily
Semax
Once daily
Administration
P21 (P021)
Intranasal (spray)
Semax
Intranasal spray
Cycle Length
P21 (P021)
8-12 weeks
Semax
4-6 weeks
Onset Speed
P21 (P021)
Gradual (3-4 weeks)
Semax
Rapid (hours to days)
Evidence Level
P21 (P021)
Strong human trials (Phase 3 or FDA approved)
Semax
Moderate human trials (Phase 1-2)
Efficacy
Benefit
ratings
Cognitive
Anti-Aging
Healing & Recovery
Cognitive Enhancement
Neuroprotection
Mental Energy
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)
Semax
Molecular Formula
C37H51N9O10S
Molecular Weight
813.9 g/mol
Half-Life
Several minutes to hours (intranasal effects persist longer)
Bioavailability
High via intranasal route (directly reaches brain)
CAS Number
80714-61-0
Protocols
Dosing
tiers
P21 (P021)
Semax
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.
Semax
Students and Knowledge Workers
If your day revolves around learning, studying, or processing complex information, Semax can be a game-changer. It enhances memory consolidation and recall while improving your ability to focus for extended periods—perfect for exam prep or demanding projects.
Those Seeking Mental Clarity
Brain fog? Semax works by boosting BDNF—the protein that helps neurons communicate effectively. Users often report feeling like the 'mental static' clears away, leaving sharper, more efficient thinking in its place.
Neuroprotection Seekers
Beyond immediate cognitive benefits, Semax offers protective effects for your brain cells. It acts as an antioxidant (especially against copper toxicity) and supports neuronal health—valuable for anyone concerned about long-term brain wellness.
Recovery Support (Under Medical Supervision)
In Russia, Semax is approved for helping stroke patients and those with traumatic brain injuries recover cognitive function. While not FDA-approved for this use elsewhere, the research shows meaningful neuroprotective and neurorestorative properties.
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
Semax
Common
- Nasal irritation
- Mild headache
- Increased alertness
Uncommon
- Temporary blood pressure increase
- 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
Semax
Evidence Level
Moderate human trials (Phase 1-2)
FDA Status
Research compound
Safety Overview
Semax has been used clinically in Russia for over 25 years with an excellent safety profile. It's approved there for treating stroke, cognitive impairment, and optic nerve diseases. Studies consistently show minimal side effects, mostly limited to mild nasal irritation when using the spray form. Unlike stimulants, Semax doesn't appear to cause tolerance, dependence, or withdrawal symptoms even with extended use.
Contraindications
- xPregnancy or planning to become pregnant
- xCurrently breastfeeding
- xHistory of seizures or epilepsy
- xKnown allergy to ACTH-related peptides
- xUncontrolled hypertension
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 Semax if...
- Cognitive enhancement
- Memory improvement
- Focus and concentration
- Neuroprotection