FGL vs P21
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
FGL
FGL (FG Loop) is a synthetic peptide that mimics the neural cell adhesion molecule (NCAM) FG loop region. It promotes neuroplasticity and has shown cognitive-enhancing effects in research.
Full details →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 →Side-by-Side Comparison
| Aspect | FGL | P21 |
|---|---|---|
| Mechanism | Binds to FGFR1 (fibroblast growth factor receptor 1) to activate downstream signaling cascades that promote neurite outgrowth, synaptic plasticity, and neuronal survival. | Inhibits glycogen synthase kinase-3β (GSK-3β) and activates CREB signaling pathway. This promotes BDNF expression, neurogenesis in the hippocampus, and synaptic plasticity. |
| Typical Dosage | Research protocols have used subcutaneous doses ranging from 1-10mg. Intranasal administration also studied. Optimal dosing not established. | Research protocols typically use 1-5mg administered intranasally or subcutaneously. Often used in cycles of 2-4 weeks. |
| Administration | Subcutaneous injection or intranasal administration. Research compound with limited human dosing data. | Can be administered intranasally for direct CNS access or subcutaneously. Best used cyclically rather than continuously. |
| Side Effects | Limited human data available. Animal studies show good tolerability. | Limited data. Reported effects include mild headache, temporary brain fog during initial use, and fatigue. |
| Best For |
What They Have in Common
Both FGL and P21 are commonly used for: