--- title: "P-21 vs PE-22-28: Side-by-Side Comparison (2026)" url: https://www.bodyhackguide.co/compare/p-21-vs-pe-22-28 description: "Compare P-21 vs PE-22-28 side by side. We earn a commission on some vendor links. Mechanism, half-life, dose range, side effects and prices. P-21 from $59.99." lang: en --- Skip to content Compare notes on r/BodyHackGuide (https://reddit.com/r/bodyhackguide) Compare notes with other researchers. Join r/BodyHackGuide (https://reddit.com/r/bodyhackguide) # P-21 vs PE-22-28 Side-by-side comparison of P-21 and PE-22-28: mechanism, half-life, dose range, safety profile, and vendor pricing. P-21 from $59.99 PE-22-28 from $54.99 ## Price snapshot ### P-21 Current low $59.99 current listings 7-day low — not enough history yet 30-day low — not enough history yet 30-day change — not enough history yet ### PE-22-28 Current low $54.99 current listings 7-day low — not enough history yet 30-day low — not enough history yet 30-day change — not enough history yet ## P-21 P-21 (also written P021, or Peptide 021) is a synthetic peptidergic compound derived from the neurotrophic region of ciliary neurotrophic factor (CNTF), designed to activate neurogenic and BDNF-producing pathways in the… **Lowest listed price:** $59.99 across 1 listing Full P-21 profile (https://www.bodyhackguide.co/compound/p-21) ## PE-22-28 PE-22-28 is a synthetic seven-amino-acid peptide (sequence PAGASRLLLLTGEIDLP derivative, commonly truncated to PE-22-28 as shorthand for "position 22-28" within the parent humanin-family sequence) that was designed as an… **Lowest listed price:** $54.99 across 1 listing Full PE-22-28 profile (https://www.bodyhackguide.co/compound/pe-22-28) ## Side-by-side comparison | Attribute | P-21 | PE-22-28 | | --- | --- | --- | | Category | Nootropics | Nootropics | | Research Stage | Preclinical | Preclinical | | Mechanism of Action | P-21 is designed to engage a subset of CNTF's biological activity — specifically the neurogenic and BDNF-inducing effects — while avoiding the JAK/STAT3 activation on peripheral CNTF receptors that causes cachexia and muscle wasting when full-length CNTF is… | PE-22-28 is a synthetic 7-amino-acid peptide (sequence GVSWGLR) and a shortened analog of spadin. Its proposed mechanism is inhibition of the TREK-1 (TWIK-related K+) channel, a two-pore-domain potassium channel (K2P2.1 / KCNK2) implicated in mood regulation.… | | Half-Life | — | Not characterized in humans. As a small 7-amino-acid peptide a short plasma half-life is expected; in mice the parent peptide spadin lost antidepressant activity by about 7 hours after a single dose, while modified analogs (e.g., G/A-PE 22-28) extended the behavioral effect to roughly 21-23 hours [PMID:28955242]. | | Typical Dose Range | 500-2000 mcg (0.5-2 mg) daily, most commonly 500-1000 mcg (community/self-experimentation range; no clinical validation) | 250-2000 mcg subcutaneous per dose (empirical research-chemical community range; no clinically validated human dose exists; effective preclinical rodent doses were far lower, ~3 mcg/kg). | | Dosing Frequency | Once daily (some users divide into twice daily), typically dosed in the morning | Once daily or every other day (research-chemical community protocols; no validated clinical dosing schedule). | | Administration | — | — | | Side Effects | The side effect profile of P-21 in humans is not documented because no clinical trials have been conducted. Rodent studies describe generally acceptable tolerability at doses producing cognitive and neurogenic effects, without obvious signs of weight loss,… | No human side-effect data exist for PE-22-28 because it has never been tested in people. What can be said comes from rodent studies of PE-22-28, spadin and their analogs, plus general considerations for injected research peptides. In the preclinical work, the… | | Molecular Weight | 578.67 g/mol (C27H42N6O8) | 773.9 g/mol | | Common Vial Sizes | — | — | ## Price tracking Tracking P-21 prices since September 5, 2026. Trend chart unlocks once we have price snapshots from more than one day. ## Price tracking Tracking PE-22-28 prices since September 5, 2026. Trend chart unlocks once we have price snapshots from more than one day. ### P-21: potential benefits - Enhanced hippocampal neurogenesis (preclinical) - Improved learning and memory (preclinical, rodent) - Elevated BDNF and other neurotrophin expression - Neuroprotective effects in Alzheimer's disease models (preclinical) - Reduced tau hyperphosphorylation and soluble amyloid-beta in transgenic mice (preclinical) ### PE-22-28: potential benefits - Antidepressant-like effects in rodent models of depression (preclinical only) - Potent, selective inhibition of the TREK-1 (K2P2.1) potassium channel (IC50 ~0.12 nM) - Rapid-onset (~4-day) antidepressant profile in animals, unlike the multi-week lag of SSRIs - Increased hippocampal neurogenesis in mice - Increased cortical synaptogenesis (PSD-95) and BDNF expression in preclinical studies - No human-validated benefits; not approved for any use (research use only) ## Frequently asked ### What's the difference between P-21 and PE-22-28? P-21 is a nootropics that p-21 is designed to engage a subset of cntf's biological activity — specifically the neurogenic and bdnf-inducing effects — while avoiding the jak/stat3 activation on peripheral…. PE-22-28 is a nootropics that pe-22-28 is a synthetic 7-amino-acid peptide (sequence gvswglr) and a shortened analog of spadin. its proposed mechanism is inhibition of the trek-1 (twik-related k+) channel, a…. The two differ in mechanism, half-life (not reported vs Not characterized in humans. As a small 7-amino-acid peptide a short plasma half-life is expected; in mice the parent peptide spadin lost antidepressant activity by about 7 hours after a single dose, while modified analogs (e.g., G/A-PE 22-28) extended the behavioral effect to roughly 21-23 hours [PMID:28955242].), and typical dose range. ### Which has the longer half-life, P-21 or PE-22-28? P-21 has a half-life of not reported. PE-22-28 has a half-life of Not characterized in humans. As a small 7-amino-acid peptide a short plasma half-life is expected; in mice the parent peptide spadin lost antidepressant activity by about 7 hours after a single dose, while modified analogs (e.g., G/A-PE 22-28) extended the behavioral effect to roughly 21-23 hours [PMID:28955242].. Longer half-lives generally mean less frequent dosing but slower on/off kinetics. ### Which is cheaper, P-21 or PE-22-28? Lowest listed price on BodyHackGuide: P-21 from $59.99, PE-22-28 from $54.99. Prices are pulled from the vendor listings tracked on BHG and change frequently. See the compare tables on each compound page for the current set of offers. ### Can you stack P-21 and PE-22-28? Stacking depends on mechanism overlap, safety profile, and goals. P-21 and PE-22-28 should only be stacked after reviewing each compound's individual protocol page, side effect profile, and any published interaction data. Use the BodyHackGuide stack builder for a structured review before combining research compounds. ## See current vendor prices Listings from the vendors we track. Prices change often, so check the vendor before you buy. P-21 prices: https://www.bodyhackguide.co/compound/p-21?tab=prices PE-22-28 prices: https://www.bodyhackguide.co/compound/pe-22-28?tab=prices Compare all compounds: https://www.bodyhackguide.co/compare ### Before you buy P-21 or PE-22-28 Check the vendor trust score. Every supplier we track is rated 0-100 on COA verification, payment transparency, shipping, reviews, and listings: one published, reproducible methodology, applied to every vendor. View Vendor Scorecard (https://www.bodyhackguide.co/vendors/scorecard) ## Related comparisons **Research use only.** BodyHackGuide is a research and price-comparison reference. The compounds discussed on this page are not approved by the FDA for human consumption and are sold strictly for laboratory research. Prices shown are pulled from vendor listings tracked on BHG and are subject to change. Every vendor is ranked on the same public, reproducible methodology. See editorial standards (https://www.bodyhackguide.co/editorial-standards) and affiliate disclosure (https://www.bodyhackguide.co/affiliate-disclosure). BodyHackGuide (https://www.bodyhackguide.co/) Your biohacking research hub: compound pricing, brain health protocols, dosing tools, and vendor reviews. support@bodyhackguide.co Join our Discord: https://discord.gg/Mhq5UdRYBA r/BodyHackGuide on Reddit: https://reddit.com/r/BodyHackGuide **Affiliate Disclosure:** We rank every vendor on the same public, reproducible methodology (https://www.bodyhackguide.co/vendors/methodology). Full details in our affiliate disclosure (https://www.bodyhackguide.co/affiliate-disclosure). **Research Disclaimer:** All compounds listed are for laboratory and research purposes only. Not for human consumption. This site does not sell or ship any products. Always consult a qualified healthcare professional and comply with local regulations. © 2026 BodyHackGuide. All rights reserved. - Terms: https://www.bodyhackguide.co/terms - Privacy: https://www.bodyhackguide.co/privacy ## Structured data ```json [ { "@context": "https://schema.org", "@type": "BreadcrumbList", "itemListElement": [ { "@type": "ListItem", "position": 1, "name": "Home", "item": "https://www.bodyhackguide.co/" }, { "@type": "ListItem", "position": 2, "name": "Compare", "item": "https://www.bodyhackguide.co/compare" }, { "@type": "ListItem", "position": 3, "name": "P-21 vs PE-22-28" } ] }, { "@context": "https://schema.org", "@type": "WebPage", "name": "P-21 vs PE-22-28: Side-by-Side Comparison (2026)", "description": "Compare P-21 vs PE-22-28 side by side. We earn a commission on some vendor links. Mechanism, half-life, dose range, side effects and prices. 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