P21 vs Noopept
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 →Noopept
Noopept (N-phenylacetyl-L-prolylglycine ethyl ester) is a peptide-derived nootropic developed in Russia. While technically a dipeptide prodrug rather than a true peptide, it's often discussed alongside peptide nootropics.
Full details →Side-by-Side Comparison
| Aspect | P21 | Noopept |
|---|---|---|
| Mechanism | Inhibits glycogen synthase kinase-3β (GSK-3β) and activates CREB signaling pathway. This promotes BDNF expression, neurogenesis in the hippocampus, and synaptic plasticity. | Metabolized to cycloprolylglycine which modulates AMPA and NMDA receptors, increases NGF and BDNF expression, and provides neuroprotective effects through antioxidant mechanisms. |
| Typical Dosage | Research protocols typically use 1-5mg administered intranasally or subcutaneously. Often used in cycles of 2-4 weeks. | Oral: 10-30mg daily, typically divided into 2-3 doses. Sublingual use may enhance absorption. Some users go higher but effects may plateau. |
| Administration | Can be administered intranasally for direct CNS access or subcutaneously. Best used cyclically rather than continuously. | Oral or sublingual administration. Unlike most peptides, it's orally bioavailable. Can be taken with or without food. |
| Side Effects | Limited data. Reported effects include mild headache, temporary brain fog during initial use, and fatigue. | Headache (often from choline depletion), irritability, insomnia if taken late, and occasional brain fog during initial use. |
| Best For |
What They Have in Common
Both P21 and Noopept are commonly used for: