GHRP-6 vs P21
Side-by-side comparison of key properties, dosing, and research.
- Summary
- GHRP-6 is the original synthetic GH-releasing peptide and a potent ghrelin receptor agonist. It produces strong GH pulses but is notorious for a significant hunger surge 30–45 minutes post-injection. This hunger side effect makes it less preferred than Ipamorelin or GHRP-2 for most protocols but can be useful in patients with appetite deficiency.
- P21 is a synthetic peptide derived from CNTF (ciliary neurotrophic factor) that promotes hippocampal neurogenesis, enhances memory and spatial learning, and may reduce amyloid-beta pathology. It is used as a neurogenic and cognitive enhancer with potential anti-Alzheimer's applications.
- Half-Life
- 15–60 minutes
- Not well characterized; likely short, but neurogenic effects persist long after administration
- Admin Route
- SubQ, Intranasal
- SubQ, Intranasal
- Research
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- Typical Dose
- 100–300 mcg
- 100–500 mcg
- Frequency
- 2–3 times daily
- Once daily
- Key Benefits
- Strong GH stimulation
- Elevated IGF-1
- Muscle growth and recovery support
- Potential anti-inflammatory effects at GI level
- Useful for patients with appetite deficiency or cachexia
- Enhanced recovery from training
- Promotes hippocampal neurogenesis
- Enhances spatial memory and learning
- Increases BDNF expression
- Reduces amyloid-beta plaque formation (animal models)
- Anti-tau pathology potential
- Cognitive enhancement without stimulant effects
- Potential therapeutic for Alzheimer's and cognitive aging
- Side Effects
- Intense hunger surge (30–45 min post-injection)
- Water retention
- Elevated cortisol (modest)
- Elevated prolactin (modest)
- +2 more
- Generally well tolerated in animal studies
- Limited human clinical data
- Injection site reactions
- Potential mild fatigue at initiation
- Stacks With
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