Cortexin

1. Overview

Cortexin is a lyophilized polypeptide complex derived from the cerebral cortex of cattle and pigs under 12 months of age, manufactured by the Russian pharmaceutical company Geropharm (St. Petersburg, Russia) [6]. It is an approved pharmaceutical in Russia and Commonwealth of Independent States (CIS) countries, widely prescribed for neurological disorders including stroke, traumatic brain injury, encephalopathy, epilepsy, cognitive impairment, and pediatric developmental delay [6].

Each vial of Cortexin contains 10 mg (adult formulation) or 5 mg (pediatric formulation) of active substance -- a complex of water-soluble polypeptide fractions with molecular weights ranging from 1,000 to 10,000 Da -- plus 12 mg of glycine as a stabilizer [6]. The polypeptide composition is predominantly acidic and neutral, with isoelectric points of 3.5 to 9.5 [6]. The preparation readily crosses the blood-brain barrier in experimental models.

Cortexin occupies a unique position in the Khavinson bioregulator landscape as the bridge between crude tissue extracts and defined synthetic peptides. It is the parent preparation from which two key synthetic bioregulators were derived: Cortagen (AEDP), identified through directed amino acid synthesis analysis [5], and Pinealon (EDR, Glu-Asp-Arg), isolated through peptide fractionation [7]. Vladimir Khavinson's discovery of these individual active components from Cortexin represents one of the core achievements of the bioregulator research program.

Cortexin is conceptually similar to Cerebrolysin (manufactured by EVER Neuro Pharma, Austria), another brain-derived polypeptide preparation. However, key differences exist: Cortexin is derived specifically from cerebral cortex tissue rather than whole brain; it is administered intramuscularly rather than intravenously; it contains larger polypeptide fractions; and its clinical evidence base, while substantial within Russia, lacks the international multicenter RCTs that characterize Cerebrolysin's evidence base [10][15].

Type

Polypeptide complex (cerebral cortex extract); not a single peptide

Composition

10 mg water-soluble polypeptide fractions (MW 1,000-10,000 Da) + 12 mg glycine (stabilizer)

Source

Cerebral cortex of cattle and pigs under 12 months of age

Manufacturer

Geropharm (St. Petersburg, Russia)

Route

Intramuscular injection (lyophilisate reconstituted in saline or procaine)

Receptor Targets

AMPA, kainate, mGluR1, GABAA1, mGluR5

Molecular Partners

Beta-5-tubulin, creatine kinase B, protein 14-3-3 alpha/beta

Russian Approval

Approved for adults and children; manufactured by Geropharm

Western Regulatory Status

Not approved by FDA, EMA, or any Western regulatory agency

2. Mechanism of Action

Cortexin's mechanism of action is pleiotropic, involving multiple receptor systems, enzymatic pathways, and molecular partners. Because it is a complex mixture rather than a single molecule, its biological activity represents the sum of multiple peptide-receptor and peptide-protein interactions.

Receptor-Level Activity

In vitro binding studies have identified that Cortexin contains compounds that interact with multiple neurotransmitter receptor systems [6]:

• AMPA receptors: Ionotropic glutamate receptors mediating fast excitatory synaptic transmission
• Kainate receptors: Ionotropic glutamate receptors involved in synaptic plasticity
• mGluR1 (metabotropic glutamate receptor 1): Coupled to phospholipase C, involved in synaptic plasticity and neuronal excitability
• GABAA1 receptors: The primary inhibitory receptor system in the brain, mediating GABAergic inhibition
• mGluR5 (metabotropic glutamate receptor 5): Involved in learning, memory, and pain processing

This dual engagement of both excitatory (glutamatergic) and inhibitory (GABAergic) receptor systems underlies Cortexin's proposed mechanism of optimizing the balance between excitation and inhibition in the brain -- a balance that is disrupted in many neurological conditions [6].

Molecular Partners and Signal Transduction

Proteomic analysis has identified three neuron-specific proteins as primary molecular partners of Cortexin peptides in the brain [3]:

1. Beta-5-tubulin: A neuron-specific tubulin isoform critical for microtubule dynamics, axonal transport, and neuronal morphology
2. Creatine kinase B: The brain-specific isoform of creatine kinase, essential for energy metabolism in neurons
3. Protein 14-3-3 alpha/beta: A regulatory protein involved in signal transduction, cell cycle control, and apoptosis prevention

These molecular interactions link Cortexin's neuroprotective effects to key processes underlying neuroplasticity: signal transduction, energy metabolism, proteolytic protein modification, cell structure, and neuroinflammation [3].

OPG/RANK/RANKL and TRPC1 Modulation (2025)

A 2025 study in Neurological Research investigated Cortexin's effects on inflammatory and calcium signaling biomarkers in a rat cerebral ischemia-reperfusion (I/R) model [16]. In rats receiving Cortexin at 1 or 2 mg/kg after I/R injury, total oxidant status (TOS) was significantly reduced and total antioxidant status (TAS) was increased compared to untreated I/R animals. At 2 mg/kg, TAS levels exceeded even control values. Immunohistochemical analysis revealed that Cortexin significantly decreased expression of OPG, RANK, RANKL (components of a critical inflammatory signaling axis), and TRPC1 (a calcium channel involved in ischemic injury). These findings identify two additional mechanistic pathways -- OPG/RANK/RANKL-mediated neuroinflammation and TRPC1-mediated calcium signaling -- through which Cortexin exerts neuroprotection, expanding the mechanistic understanding beyond its previously characterized receptor targets [16].

Caspase-8 Inhibition (Anti-Apoptotic Mechanism)

A specific anti-apoptotic mechanism was identified showing that Cortexin effectively inhibits brain caspase-8, the initiator protease of the extrinsic (death receptor-mediated) apoptotic pathway [2]. Importantly, Cortexin's effects on other proteases (caspase-1, -3, -9, cathepsin B, and calpain) were much less pronounced or absent, indicating selectivity for the extrinsic apoptotic pathway rather than a nonspecific protease-inhibitory effect [2]. This selective caspase-8 inhibition may be particularly relevant in ischemic injury, where death receptor activation contributes significantly to neuronal loss.

Neurotrophic and GABAergic Effects

The mechanism of action as described in the Russian product information includes [6]:

• Activation of neuropeptides and neurotrophic cerebral factors
• Optimization of the balance between excitatory and inhibitory amino acid metabolism, including dopamine and serotonin
• GABAergic (inhibitory) effect reducing seizure activity
• Reduction of paroxysmal convulsive activity
• Antioxidant activity through prevention of free radical formation

Serotonin System Modulation

Short peptides derived from brain cortex tissue, including those present in Cortexin, have been shown to stimulate serotonin expression in cortical cells [14], providing a potential mechanism for the mood and emotional stability effects observed clinically.

3. Researched Applications

Acute Ischemic Stroke

Evidence level: Russian clinical use; preclinical comparative studies

Cortexin is approved in Russia for acute ischemic stroke and is administered at 10 mg twice daily (morning and afternoon) intramuscularly for 10 days, with a second course after a 10-day interval [6]. In the approved stroke protocol, the higher dosing frequency reflects the clinical urgency of the condition.

In a comparative preclinical study, Cortexin at 1 or 3 mg/kg demonstrated neuroprotective efficacy in models of both acute and chronic brain ischemia in rats, with efficacy comparable to Cerebrolysin and Actovegin [1]. The effectiveness in chronic ischemia models is particularly relevant given the ongoing neurodegeneration that occurs in the weeks and months following stroke.

A 2025 clinical study evaluated Cortexin in 30 young patients (aged 18-45 years) with poststroke cognitive impairment following ischemic stroke in the carotid system [17]. After two courses of Cortexin, Montreal Cognitive Assessment (MoCA) scores improved significantly from 25.1 to 28.4 points, with gains in attention, short-term memory, and executive functions maintained at follow-up (28.0 points). SF-36 quality of life scores also improved significantly. Cortexin was described as effective, safe, and well tolerated in this younger adult population -- a demographic that has been understudied in Cortexin research, which has historically focused on elderly patients [17].

Traumatic Brain Injury

Evidence level: Russian approved indication; preclinical

Cortexin is indicated for craniocerebral trauma and its consequences in the Russian approval [6]. The standard dosing protocol (10 mg IM daily for 10 days) is used in the post-acute phase of TBI management.

Encephalopathy

Evidence level: Russian approved indication

Various forms of encephalopathy are listed among Cortexin's approved indications, including vascular encephalopathy, toxic encephalopathy, and encephalopathies of other origins [6]. The broad indication reflects the preparation's pleiotropic mechanism affecting multiple neurological pathways.

Epilepsy

Evidence level: Russian approved indication

Cortexin's GABAergic effect and reduction of paroxysmal convulsive brain activity form the basis for its approved indication in epilepsy [6]. It is used as adjunctive therapy alongside conventional antiepileptic medications rather than as monotherapy.

Cognitive Disorders

Evidence level: Russian approved indication

Cortexin is indicated for cognitive disturbances including memory and thinking impairment [6]. The mechanism is proposed to involve optimization of neurotransmitter balance and restoration of neuroplasticity through the molecular partner interactions described above [3].

Pediatric Neurodevelopmental Conditions

Evidence level: Russian approved indication; preclinical

Cortexin is approved for use in children for delayed psychomotor and speech development, various forms of cerebral palsy, and decreased learning ability [6]. A 2025 preclinical study confirmed neurotropic effects in rodent models of developmental delay induced by both prenatal ethanol exposure and neonatal ischemia-hypoxia, providing experimental support for the pediatric indications [4].

The pediatric formulation (5 mg) is dosed at 0.5 mg/kg for children weighing up to 20 kg, and at the standard 10 mg dose for children over 20 kg, both for 10-day courses [6].

Encephalitis and Encephalomyelitis

Evidence level: Russian approved indication

Both acute and chronic forms of encephalitis and encephalomyelitis are listed among Cortexin's approved indications [6].

4. Clinical Evidence Summary

5. Dosing in Research

Administration Method

Cortexin is supplied as a lyophilisate (freeze-dried powder) that must be reconstituted before intramuscular injection. The contents of one vial are dissolved in 1-2 mL of one of the following solutions [6]:

• 0.5% procaine (novocaine) solution
• Water for injection
• 0.9% sodium chloride (normal saline)

The injection is administered once daily (or twice daily for stroke) intramuscularly. Cortexin is not administered intravenously -- this distinguishes it from Cerebrolysin, which is given by IV infusion.

Course Structure

The standard treatment course is 10 consecutive days. For stroke, courses may be repeated after a 10-day interval. For chronic conditions, courses are typically repeated every 3-6 months based on clinical response.

6. Safety and Side Effects

Clinical Safety Profile

Cortexin has been used clinically in Russia for several decades with an established safety profile within the Russian pharmacovigilance system. The approved product information lists the following [6]:

Contraindications:

• Individual hypersensitivity to Cortexin or its components
• Pregnancy (insufficient data)
• Breastfeeding (insufficient data)

Adverse reactions:

• Individual hypersensitivity reactions (rare)
• No other specific adverse reactions listed in the Russian prescribing information

Comparison with Cerebrolysin Safety Data

While Cortexin itself lacks the international pooled safety analyses available for Cerebrolysin, the conceptual similarity between the two preparations provides some context. Cerebrolysin's pooled safety analysis across multiple RCTs showed adverse event rates comparable to placebo, with the most common events being dizziness, headache, and injection site reactions [10][15]. Cortexin's safety profile is expected to be similar given its analogous composition.

Important Limitations

• No international regulatory review (FDA, EMA) of safety data
• No formal drug interaction studies
• Safety in pregnancy and lactation not established
• Long-term safety data not available in peer-reviewed international literature
• As a biological product derived from animal tissue, theoretical concerns about prion disease transmission, immunogenicity, and batch variability apply, though no such events have been reported
• The addition of procaine (novocaine) as a reconstitution solvent introduces additional pharmacological activity and allergenic potential at the injection site

7. Cortexin vs. Cerebrolysin

Given the frequent comparison between these two brain-derived polypeptide preparations, a systematic comparison is warranted:

| Feature | Cortexin | Cerebrolysin | |---------|----------|--------------| | Source tissue | Cerebral cortex specifically | Whole porcine brain (enzymatic proteolysis) | | Species | Cattle and pigs | Pigs | | MW range | 1,000-10,000 Da | All components below 10,000 Da | | Composition | ~70-95% polypeptides | ~75% free amino acids, ~25% peptides | | Route | Intramuscular | Intravenous or intramuscular | | Manufacturer | Geropharm (Russia) | EVER Neuro Pharma (Austria) | | Regulatory approvals | Russia, CIS | 50+ countries (not FDA) | | RCT evidence | Limited, primarily Russian | Extensive (160+ clinical studies, 8000+ patients) | | Cochrane reviews | None | Two (stroke and vascular dementia) | | Derived synthetic peptides | Cortagen (AEDP), Pinealon (EDR) | None identified | | Clinical doses | 10 mg/day IM | 10-50 mL/day IV |

Both preparations share the fundamental concept of brain-derived neuropeptide therapy but differ significantly in their regulatory rigor, evidence base, and international accessibility [10][15].

8. Pharmacokinetics

Cortexin's pharmacokinetic profile is better characterized than most Khavinson preparations due to its pharmaceutical status and intramuscular route of administration, though formal pharmacokinetic studies meeting Western regulatory standards have not been published.

The preparation is administered intramuscularly, bypassing gastrointestinal degradation and providing relatively high systemic bioavailability for the peptide components. The polypeptide fractions (MW 1,000-10,000 Da) are expected to enter systemic circulation via capillary absorption from the injection site. The 12 mg glycine stabilizer may facilitate peptide absorption and provide additional neuroprotective activity (glycine is an inhibitory neurotransmitter) [6].

Blood-brain barrier penetration has been described as positive in experimental models, consistent with the preparation's CNS-targeted clinical effects [6]. The specific transport mechanisms (whether via receptor-mediated transcytosis, paracellular pathways, or passive diffusion of smaller peptide fractions) have not been fully elucidated. The acidic and neutral isoelectric point profile (3.5-9.5) of Cortexin's peptide components may facilitate interaction with cationic transporters at the BBB.

No formal PK parameters (Cmax, Tmin, AUC, half-life, volume of distribution, clearance) have been published for Cortexin or its individual peptide components. The standard 10-day treatment course suggests that repeated daily dosing is needed to achieve sustained pharmacological effects, consistent with a gene-expression-level mechanism that requires time to manifest functionally.

9. Dose-Response

Cortexin's approved dosing reflects some degree of dose optimization within the Russian regulatory framework, though formal dose-response data from controlled trials are limited.

The approved adult dose is 10 mg once daily (or twice daily for acute stroke), while the pediatric dose is weight-based at 0.5 mg/kg for children under 20 kg [6]. This weight-based pediatric dosing implies that some dose proportionality has been established, though the specific dose-finding studies are not available in English-language literature.

In the preclinical neuroprotection study, Cortexin showed efficacy at both 1 and 3 mg/kg in rat ischemia models [1], suggesting a dose range rather than a single optimal dose. The higher dose (3 mg/kg) did not show dramatically greater efficacy than the lower dose, potentially suggesting a plateau in the dose-response curve.

The decision to use double-frequency dosing (10 mg twice daily) for acute stroke compared to standard single daily dosing for other indications represents a clinical dose adjustment based on disease severity, though the pharmacological rationale (faster onset, higher steady-state levels, or both) has not been explicitly characterized.

10. Comparative Effectiveness

Cortexin vs. Cerebrolysin

This is the most clinically relevant comparison. Both are brain-derived polypeptide preparations used for similar neurological indications. A direct comparative preclinical study showed Cortexin at 1-3 mg/kg was effective in both acute and chronic brain ischemia models, with efficacy comparable to Cerebrolysin and Actovegin [1]. Key differences include: Cerebrolysin has extensive international RCT data (8,000+ patients, Cochrane reviews), while Cortexin's evidence is primarily Russian; Cerebrolysin is given IV (allowing higher doses), while Cortexin is IM; and Cerebrolysin contains predominantly free amino acids (~75%), while Cortexin contains predominantly intact polypeptides (~70-95%).

Cortexin vs. Cortagen (AEDP)

Cortagen is the single defined tetrapeptide derived from Cortexin. Cortexin's advantage is its multi-component nature (potentially broader therapeutic coverage through multiple receptor interactions) and clinical approval. Cortagen's advantage is molecular precision, enabling specific mechanistic studies. The clinical effects of Cortexin likely exceed those attributable to any single peptide component.

Cortexin vs. Standard Neuroprotective Agents

No controlled comparative trials between Cortexin and internationally approved neuroprotective agents (e.g., edaravone for stroke, memantine for dementia) have been published. The pharmacological profiles are fundamentally different: Cortexin acts through multiple receptor systems and anti-apoptotic pathways simultaneously, while conventional agents target single receptors or enzymes.

11. Enhanced Safety

Cortexin has the most extensive clinical safety record among Khavinson preparations, reflecting decades of pharmaceutical use in Russia. The approved prescribing information lists individual hypersensitivity as the only reported adverse reaction, with no specific adverse events identified beyond rare allergic responses [6].

As a biological extract from animal tissue, theoretical safety concerns include prion disease transmission, immunogenic reactions, and batch variability. No such events have been reported in published literature. The use of young animal tissue (under 12 months) and the manufacturing process (acid hydrolysis, ultrafiltration) provide some mitigation against prion risk.

The use of procaine (novocaine) as a reconstitution solvent introduces additional pharmacological considerations -- procaine is a local anesthetic with its own adverse effect profile (allergic reactions, CNS toxicity at high doses) and drug interactions. Alternative reconstitution in saline or water for injection avoids this issue.

Specific safety gaps include the absence of international regulatory review (FDA, EMA), formal drug interaction studies, and safety data in pregnancy and lactation. The selective caspase-8 inhibition [2] is a specific anti-apoptotic mechanism that warrants long-term safety consideration, though no oncological concerns have emerged in decades of clinical use. The pediatric approval status, while reflecting clinical experience, is not supported by the rigor of ICH-compliant pediatric safety studies.

12. Related Peptides

See also: Cerebrolysin, Cortagen, Cerluten, Semax

13. References

1. [1] Silachev DN, Shram SI, Shakova FM, Romanova GA, Myasoedov NF. (2021). Neuroprotective action of Cortexin, Cerebrolysin and Actovegin in acute or chronic brain ischemia in rats. PLoS ONE. DOI PubMed
2. [2] Khavinson VKh, Grigoriev EI, Malinin VV, Ryzhak GA. (2017). Peptide drug Cortexin inhibits brain caspase-8. Biochemistry (Moscow), Supplement Series B: Biomedical Chemistry. DOI PubMed
3. [3] Khavinson VKh, Ryzhak GA. (2018). Molecular mechanisms of brain peptide-containing drugs: Cortexin. Advances in Gerontology. PubMed
4. [4] Rybalkina OY, Nesmeyanova EV, Churnosov MI, Averkova IA. (2025). Neurotropic effects of Cortexin on models of mental and physical developmental delay. Biomedicines. DOI PubMed
5. [5] Anisimov SV, Boheler KR, Anisimov VN, Khavinson VKh. (2004). Elucidation of the effect of brain cortex tetrapeptide Cortagen on gene expression in mouse heart by microarray. Biogerontology. DOI PubMed
6. [6] Geropharm. (2024). Cortexin product information. Geropharm official product portfolio.
7. [7] Khavinson VKh. (2002). Peptides and Ageing. Neuro Endocrinology Letters. PubMed
8. [8] Khavinson VKh, Anisimov VN. (2000). Peptide bioregulation of aging: results and prospects. Biogerontology. DOI PubMed
9. [9] Linkova NS, Khavinson VKh. (2019). Epigenetic mechanisms of peptide-driven regulation and neuroprotective protein FKBP1b. Molecular Biology. DOI
10. [10] Ziganshina LE, Abakumova T, Hoyle CH. (2023). Cerebrolysin for acute ischaemic stroke. Cochrane Database of Systematic Reviews. DOI PubMed
11. [11] Fedoreyeva LI, Kireev II, Khavinson VKh, Vanyushin BF. (2011). Penetration of short fluorescence-labeled peptides into the nucleus in HeLa cells and in vitro specific interaction of the peptides with deoxyribooligonucleotides and DNA. Biochemistry (Moscow). DOI PubMed
12. [12] Khavinson VKh, Morozov VG. (2003). Peptides of pineal gland and thymus prolong human life. Neuro Endocrinology Letters. PubMed
13. [13] Khavinson VKh. (2013). Peptide bioregulators: the new class of geroprotectors. Advances in Gerontology. DOI PubMed
14. [14] Khavinson VKh, Linkova NS, Tarnovskaya SI. (2014). Short peptides stimulate serotonin expression in cells of brain cortex. Bulletin of Experimental Biology and Medicine.
15. [15] Masliah E, Diez-Tejedor E. (2021). Cerebrolysin for stroke, neurodegeneration, and traumatic brain injury: review of the literature and outcomes. Drugs of Today. DOI PubMed
16. [16] Kaya A, et al. (2025). Cortexin modulates OPG/RANK/RANKL and TRPC1 expression in cerebral ischemia-reperfusion injury. Neurological Research. DOI
17. [17] Neuroscience and Behavioral Physiology authors. (2025). Poststroke cognitive impairment in young patients. Neuroscience and Behavioral Physiology. DOI