P21 vs Cortexin
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
P21
P21 is a synthetic peptide derived from Cerebrolysin, specifically designed to mimic the neurotrophic effects of the parent compound. It promotes neurogenesis and has shown cognitive-enhancing properties in research.
Full details →Cortexin
Cortexin is a polypeptide complex derived from pig brain cortex, used clinically in Russia and Eastern Europe for neurological conditions including stroke recovery, traumatic brain injury, and cognitive decline.
Full details →Side-by-Side Comparison
| Aspect | P21 | Cortexin |
|---|---|---|
| Mechanism | Inhibits glycogen synthase kinase-3β (GSK-3β) and activates CREB signaling pathway. This promotes BDNF expression, neurogenesis in the hippocampus, and synaptic plasticity. | Contains a mixture of neuropeptides and amino acids that support neuronal metabolism, provide neuroprotection, and enhance synaptic transmission. Specific mechanisms not fully characterized. |
| Typical Dosage | Research protocols typically use 1-5mg administered intranasally or subcutaneously. Often used in cycles of 2-4 weeks. | Clinical protocols: 10mg intramuscularly once daily for 10-20 days. May be repeated after 3-6 month interval. |
| Administration | Can be administered intranasally for direct CNS access or subcutaneously. Best used cyclically rather than continuously. | Intramuscular injection. Comes as lyophilized powder requiring reconstitution. Treatment given in courses rather than continuously. |
| Side Effects | Limited data. Reported effects include mild headache, temporary brain fog during initial use, and fatigue. | Generally well-tolerated. May cause injection site reactions or mild allergic responses in sensitive individuals. |
| Best For |
What They Have in Common
Both P21 and Cortexin are commonly used for: