P21 vs Human Growth Hormone (HGH)
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 →Human Growth Hormone (HGH)
Human Growth Hormone (somatropin) is a 191-amino acid protein identical to naturally produced GH. FDA-approved for growth hormone deficiency, Turner syndrome, and other conditions. Widely used off-label for anti-aging and performance.
Full details →Side-by-Side Comparison
| Aspect | P21 | Human Growth Hormone (HGH) |
|---|---|---|
| Mechanism | Inhibits glycogen synthase kinase-3β (GSK-3β) and activates CREB signaling pathway. This promotes BDNF expression, neurogenesis in the hippocampus, and synaptic plasticity. | Binds to GH receptors throughout the body, stimulating IGF-1 production in the liver. Promotes protein synthesis, fat metabolism, and cellular regeneration across multiple tissues. |
| Typical Dosage | Research protocols typically use 1-5mg administered intranasally or subcutaneously. Often used in cycles of 2-4 weeks. | Medical: 0.1-0.3mg/kg/week divided into daily doses. Anti-aging: 1-2 IU daily. Performance: 2-6 IU daily, sometimes higher. |
| Administration | Can be administered intranasally for direct CNS access or subcutaneously. Best used cyclically rather than continuously. | Subcutaneous injection, preferably at night to mimic natural pulsatile release. Rotate injection sites. Store refrigerated. |
| Side Effects | Limited data. Reported effects include mild headache, temporary brain fog during initial use, and fatigue. | Joint pain, water retention, carpal tunnel syndrome, potential insulin resistance, and acromegaly features with long-term high doses. |
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