Cortexin vs Selank
Bovine cerebral cortex-derived polypeptide preparation with nootropic, neuroprotective, and antioxidant properties used clinically in Russia for cerebrovascular disorders, cognitive impairment, and pediatric neurology
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 [1][4].
Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team · Editorial standards
Quick comparison
Dose range
Cortexin
10–10 mg
Selank
900–2700 mcg/day
Frequency
Cortexin
Once daily
Selank
3 times daily
Administration
Cortexin
Intramuscular (IM) injection
Selank
Intranasal
Cycle length
Cortexin
8-12 weeks
Selank
14 days, repeatable after 1-3 weeks
Onset speed
Cortexin
Moderate (1-2 weeks)
Selank
Rapid (hours to days)
Evidence level
Cortexin
Limited human trials
Selank
Limited human trials
Benefit ratings
Brain Recovery
Cognitive Function
Neuroprotection
Anxiety Relief
Cognitive Enhancement
Immune Support
Compound specifications
Cortexin
Molecular formula
Complex mixture — no single molecular formula (contains multiple low molecular weight polypeptide fractions, L-amino acids, vitamins, and trace elements)
Molecular weight
Low molecular weight water-soluble polypeptide fractions — specific molecular weight distribution varies as a complex biological mixture
Half-life
Approximately 2-6 hours (varies by route of administration)
Bioavailability
~85-100% (intramuscular injection)
CAS number
Not assigned (biological mixture)
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
Dosing compared
Cortexin
Intramuscular
10 mg
Once daily · 10 days per course; repeat in 3-6 months if needed
The standard adult dose per the manufacturer instructions. The 10 mg vial is dissolved in 1-2 mL of saline, water for injection, or 0.5% procaine and injected into a muscle. Children under 20 kg get 0.5 mg/kg. [6]
Selank
Intranasal
Registered label dose
900 mcg/day total (3 doses of 300 mcg)
2 drops in each nostril, 3 times daily · Registered label dose
The approved dose on the Russian registration (ЛРС-003338/09): 2 drops in each nostril, three times a day. At 75 mcg per drop that is 300 mcg per administration and 900 mcg across the day, taken as a 14-day course that can be repeated after 1-3 weeks [7]. Human evidence, registered label.
Highest dose studied
2,700 mcg/day total (3 doses of 900 mcg)
900 mcg (12 drops) 3 times daily · Highest dose studied
The top of the range the developing institute describes as optimal — single doses of 300-900 mcg, 900-2,700 mcg a day split across three administrations — and the dose used in the multicentre generalised-anxiety and neurasthenia trial, where 2,700 mcg/day was compared against medazepam 30 mg/day for 14 days [9]. Because the label caps a single administration at 2-3 drops per nostril, a 900 mcg dose is given as 2-3 drops per nostril with the rest 15 minutes later [7]. Human evidence, trial protocol.
Subcutaneous injection
Community suggestion — not a studied protocol
300-500 mcg per injection
Once daily · Community suggestion — not a studied protocol
Community-reported, not peer-reviewed. No human study has tested subcutaneous selank and the registered product is nasal drops only [7], so this range comes from community and clinical-practice reports rather than a trial — there is no published safety or effectiveness data behind it. Two things worth knowing before choosing the route. The nasal spray is absorbed almost completely, with 92.8% of the dose reaching the bloodstream within 30 seconds [7], so injecting is not a way to get more of the peptide in. And in mice, the injected and intranasal routes did not act the same: injection shifted GABA-receptor binding while the nasal route shifted NMDA-receptor binding instead, which the authors put down to how each route is absorbed and broken down [13]. That is animal work, and no one has checked whether the same split happens in people.
Best suited for
Cortexin
Cognitive support in chronic cerebral ischemia and cerebrovascular disease
Cortexin is particularly well-suited for individuals focused on cognitive support in chronic cerebral ischemia and cerebrovascular disease. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [5].
Neuroprotection and neurorecovery following stroke or traumatic brain injury
Cortexin is particularly well-suited for individuals focused on neuroprotection and neurorecovery following stroke or traumatic brain injury. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [7].
Pediatric neurology including cerebral palsy and developmental delays
Cortexin is particularly well-suited for individuals focused on pediatric neurology including cerebral palsy and developmental delays. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [7][8].
Adjunctive treatment in epilepsy management
Cortexin is particularly well-suited for individuals focused on adjunctive treatment in epilepsy management. Research and clinical experience suggest meaningful benefits in this area when used as part of a comprehensive treatment approach [7][8].
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 [1].
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 [1][2].
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 [2]. 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 [4]. It works with your body's existing systems rather than overriding them like synthetic drugs.
Side effects
Cortexin
Common
- Injection site reactions
- Headache
- Dizziness
- Nausea
- Agitation or restlessness
- Transient blood pressure changes
Uncommon
- Allergic reactions
Serious
- Severe allergic reaction / Anaphylaxis
Selank
Common
- Nasal irritation
- Mild fatigue
- Mild headache
- Injection site redness
Uncommon
- Vivid dreams
- Dizziness
Serious
- Allergic reaction
Safety & evidence
Cortexin
Evidence level
Limited human trials
FDA status
Research compound
Safety overview
Cortexin is a porcine brain-derived polypeptide preparation used in Russian neurology that is not FDA-approved and has no Western rigorous safety data. As an undefined mixture of peptides and proteins extracted from animal brains, batch standardization and quality control are not guaranteed. Concerns include potential transmissible spongiform encephalopathy (TSE/prion) risk from animal CNS tissue, although documented cases have not been reported. Allergic reactions to porcine proteins are possible. No formal human safety assessments, toxicology studies, or clinical trials by modern regulatory standards have been conducted. Use in Western countries is essentially non-existent due to regulatory limitations on animal-derived neurological products.
Contraindications
- Known hypersensitivity to Cortexin or any component including glycine stabilizer
- Allergy to bovine-derived biological products
- Pregnancy — insufficient safety data for use during pregnancy
- Breastfeeding — insufficient data on excretion into breast milk
Selank
Evidence level
Limited human trials
FDA status
Research compound
Safety overview
The safety record comes from small Russian trials, and the numbers are worth seeing. In the 62-person generalised-anxiety and neurasthenia trial, 30 people took selank at 2,700 mcg a day and 32 took medazepam 30 mg a day for 14 days; the two calmed anxiety about equally, and selank also reduced fatigue where the benzodiazepine did not [9]. A second trial of 60 people with phobic-anxiety and somatoform disorders compared it with phenazepam and reported a clear anxiolytic effect that lasted about a week after the last dose [3]. The registered label lists only two side effects — an unpleasant taste when the drops run from the nose into the throat, and allergic reactions in people sensitive to the ingredients — and records no cases of overdose, which it attributes to how fast the peptide breaks down [7]. Neither trial published a per-arm adverse-event rate, so there is no side-effect percentage to compare against placebo.
Contraindications
- Pregnancy or planning to become pregnant
- Currently breastfeeding
- Known allergy to peptide components
- Children and adolescents
- Severe psychiatric disorders requiring immediate intervention
Which is right for you?
Choose Cortexin if...
- Cognitive support in chronic cerebral ischemia and cerebrovascular disease
- Neuroprotection and neurorecovery following stroke or traumatic brain injury
- Pediatric neurology including cerebral palsy and developmental delays
- Adjunctive treatment in epilepsy management
Choose Selank if...
- Anxiety relief without sedation
- Cognitive enhancement and focus
- Memory improvement
- Stress resilience