PE-22-28 Dosage Guide

Protocols for the spadin-derived TREK-1 blocker studied as a fast-acting antidepressant: intranasal and subcutaneous dosing, what the animal research actually shows, cycling, stacking, and safety.

Compiled by PeptideWiki Editorial Team·Last reviewed August 5, 2026

What Is PE-22-28?

PE-22-28 is a synthetic seven-amino-acid peptide derived from spadin. Spadin is itself a fragment of the propeptide, a short chain of amino acids cut loose when the sortilin protein is processed inside the cell. The “PE” in the name refers to that propeptide, and “22-28” are the positions of the seven amino acids taken from it.

PE-22-28 is not a PACAP fragment. Vendor listings and secondhand write-ups frequently describe it as “PACAP(22-28),” a PAC1-selective fragment of Pituitary Adenylate Cyclase-Activating Polypeptide. That molecule does not exist. PE-22-28 has no structural or pharmacological relationship to PACAP and acts on no PACAP receptor. It is a channel blocker, not a receptor agonist. If you arrived here from a product page making that claim, the product page is wrong.

What PE-22-28 actually does is block TREK-1, a background potassium channel found throughout the brain. Background channels leak potassium out of neurons continuously, which keeps those neurons harder to fire. Blocking TREK-1 removes part of that brake and makes neurons slightly more excitable. TREK-1 is the only target it has been characterised against; no broad off-target screen has been published, so “its known mechanism” is more accurate than “its only mechanism.”

Researchers pursued this target for one reason. Mice bred without a working TREK-1 gene turn out to be naturally resistant to depression, which made a TREK-1 blocker a candidate for a genuinely new class of antidepressant. Spadin was the first such peptide, described in 2010. PE-22-28 came out of studying what spadin breaks down into in the blood, and it turned out to be the better molecule: it blocks TREK-1 at an IC50 of 0.12 nM against spadin’s 40–60 nM, several hundred times more potent, and it lasts substantially longer. Across PE-22-28 and the modified versions tested alongside it, action duration reached up to 23 hours in mice against spadin’s roughly 7. The 23-hour figure is the best result in that set rather than a measurement of the plain peptide, so treat it as the ceiling for the family, not a spec for what you buy.

The research on PE-22-28 is about depression, not cognition or brain protection. It has been tested in rodent behavioural models, and it produces new neuron growth in the hippocampus and new synapse formation in cortical neurons. All of it is animal work, and all of it was done by injection. No human has been studied.

Use our Peptide Dosage to calculate your exact dose based on vial size and concentration.

Dosing information in this guide comes from community practice, not from the published research. Every study was performed in rodents using intravenous or intraperitoneal injection, and none of it establishes a human dose by any route.

Key Characteristics:

Spadin-derived heptapeptide — 7 amino acids taken from the sortilin propeptide; unrelated to PACAP despite frequent mislabelling as PACAP(22-28)
TREK-1 potassium channel blocker — IC50 of 0.12 nM, several hundred times more potent than spadin, and longer-lasting; duration across the peptide and its modified versions reached up to 23 hours in mice
Studied as a fast-acting antidepressant — rodent models show effects after roughly 4 days, against the 2 to 4 weeks typical of conventional antidepressants
Downstream effects — increased BDNF, new neuron growth in the hippocampus, and new synapse formation, all following from channel blockade rather than direct receptor activation
Dosage range: 100–500 mcg intranasal — 1–2 times daily; subcutaneous at 100–300 mcg daily as an alternative route. Both are community conventions, not research-derived doses.
No human data of any kind — no clinical trials, no pharmacokinetics, no safety monitoring; every published result is preclinical, and the whole-animal work used injection

New to peptides? Start with the Beginner's Guide to Peptides.

How PE-22-28 Dosage Is Determined

PE-22-28 dosing is not supported by human data of any kind. There are no published dose-response studies, no pharmacokinetic profiles, and no safety trials in people. The honest description of where community doses come from is that someone picked a starting number and others copied it. This section explains what the research does establish, why it cannot be converted into a human dose, and how to think about that gap.

What the Research Actually Measured

Spadin, the parent compound, was described in 2010 as a peptide released during sortilin processing that blocks TREK-1 with an affinity of around 10 nM. A four-day course of intravenous spadin in mice produced antidepressant-like behaviour across five separate tests, along with increased CREB phosphorylation and new neuron growth in the hippocampus, both markers normally associated with weeks of SSRI treatment.

PE-22-28 was designed in 2017 by studying what spadin breaks down into in the bloodstream. It blocks TREK-1 more tightly than spadin (0.12 nM against 40–60 nM) and lasts substantially longer. It reduced immobility time in the forced swimming test, shortened latency to feed in the novelty-suppressed feeding test after four days of treatment, produced new neuron growth after that same four-day course, and increased PSD-95, a marker of synapse formation, in cultured cortical neurons.

Why Animal Doses Do Not Convert

The whole-animal studies above dosed rodents by injection, at amounts scaled to body weight; the rest of the evidence comes from cultured neurons and brain slices, which carry no dosing information at all. The community uses fixed microgram doses delivered into the nose. There is no published intranasal study of PE-22-28, no human pharmacokinetic data, and no bioavailability figure for any route in humans. Converting between those two situations is not a calculation anyone can currently perform. Anyone presenting a human dose as derived from the research is overstating what the research contains.

Community-Derived Dosing

The 100–500 mcg intranasal range used in the community is empirical. Users have titrated upward from low starting doses (100 mcg) based on subjective effects and tolerance. Figures above 500 mcg appear in some protocols but are not supported by anything published on PE-22-28.

Strength of evidence: Limited. PE-22-28 is a well-characterised molecule in rodents and an uncharacterised one in humans. There are no human trials, no pharmacokinetic data, and no dose-response curve. The numbers in this guide describe what people do, not what research supports. Treat every protocol here as a record of community practice.

Standard PE-22-28 Dosage Ranges

PE-22-28 is administered intranasally (the primary community route) or by subcutaneous injection. Intranasal is preferred on the reasoning that TREK-1 sits in the central nervous system and nose-to-brain delivery favours a target there. That reasoning is plausible but untested for this peptide: the published work used injection exclusively.

Intranasal Dosage by Experience Level

Level	Dose per Administration	Frequency	Daily Total	Notes
Beginner	100–200 mcg IN	1x daily (morning)	100–200 mcg	Assess tolerance for 1–2 weeks before increasing; ideal starting point
Intermediate	200–300 mcg IN	1–2x daily	200–500 mcg	Standard protocol for most users; morning + early afternoon if dosing twice
Advanced	300–500 mcg IN	1–2x daily	300–1000 mcg	Upper range; nothing published supports a benefit above 500 mcg/day

Subcutaneous Dosage by Experience Level

Level	Dose per Injection	Frequency	Daily Total	Notes
Beginner	100 mcg SubQ	1x daily	100 mcg	Conservative start; assess tolerance before increasing
Intermediate	150–200 mcg SubQ	1x daily	150–200 mcg	Standard subcutaneous protocol
Advanced	200–300 mcg SubQ	1x daily	200–300 mcg	Upper range for SubQ; diminishing returns likely above 300 mcg

Administration Timing

Morning administration preferred: the common community practice. Some users report a mild stimulatory quality, which is at least consistent with a compound that increases neuronal excitability
If dosing twice daily: Morning + early afternoon (e.g., 8 AM + 1 PM); avoid late evening dosing, since the same excitability effect may interfere with sleep
Intranasal technique matters: Clear nasal passages before administering, tilt head slightly forward, aim spray toward outer nasal wall (not septum), sniff gently. Do not inhale forcefully
No fasting requirement: Unlike GHRPs, PE-22-28 has no established interaction with food intake by either route

Start low and assess: Because PE-22-28 has no established clinical dosing, a conservative start at 100–200 mcg daily is strongly recommended. Titrate upward only after 1–2 weeks of consistent use with no adverse effects. There is no evidence that higher doses produce proportionally greater effects.

Verified sources for PE-22-28

These vendors are vetted by PeptideWiki for purity testing and COA transparency.

SwissChemsThird-party tested research peptides10% off

SwissChems10% off

Limitless BiotechPremium nootropics & research peptides15% off

Limitless Biotech15% off

CH PeptidesResearch-grade peptides with COA transparency10% off

CH Peptides10% off

View all vendor deals·Affiliate links. Commission at no extra cost.

Intranasal vs. Subcutaneous Administration

Route matters for PE-22-28 because TREK-1 is expressed throughout the central nervous system, so brain exposure is what the compound is aiming for. It is worth knowing that TREK-1 is not exclusively a brain channel: it is also present in the heart, which makes systemic exposure a separate consideration rather than simply a less efficient path to the same place.

Parameter	Intranasal (IN)	Subcutaneous (SubQ)
CNS Access	Direct in principle — olfactory and trigeminal nerve transport bypasses the blood-brain barrier	Indirect — must cross the blood-brain barrier from systemic circulation
Bioavailability	Unmeasured for this peptide; nasal absorption generally depends on technique, nasal health, and formulation	More consistent — reliable systemic absorption
Published Research Use	None	Injection is the studied route (intravenous and intraperitoneal, in rodents)
Community Preference	Primary route for PE-22-28	Alternative route; less commonly reported
Ease of Use	Non-invasive; no needles; requires nasal spray device	Requires syringes; injection technique; more preparation
Dose Range	100–500 mcg, 1–2x daily	100–300 mcg, 1x daily
Key Consideration	Technique-dependent; nasal health affects absorption	Greater systemic exposure, including to TREK-1 outside the brain

The intranasal preference is an inference, not a finding. No published study has administered PE-22-28 intranasally. Every result described anywhere in this guide comes from injected dosing in rodents. The community route rests on the general principle that nose-to-brain delivery favours central targets, which is a reasonable starting assumption and not a demonstrated advantage for this specific peptide.

Preparing an Intranasal Solution

PE-22-28 for intranasal use is typically reconstituted with bacteriostatic water or sterile saline (0.9% NaCl) and transferred to a nasal spray bottle. Most nasal spray devices deliver approximately 0.1 mL (100 microliters) per spray actuation. You can calculate the concentration needed based on your target dose per spray.

Intranasal Preparation Example:

Vial size in this example: 5 mg (5,000 mcg) of PE-22-28
Reconstitution volume: 2.5 mL bacteriostatic water
Concentration: 5,000 mcg ÷ 2.5 mL = 2,000 mcg per mL
Spray device delivers: 0.1 mL per spray
Dose per spray: 2,000 × 0.1 = 200 mcg per spray
For 200 mcg: 1 spray — For 400 mcg: 2 sprays (1 per nostril)

Calculate Your PE-22-28 Dose

PE-22-28 is supplied as a lyophilized (freeze-dried) powder in a range of vial sizes. For subcutaneous injection, reconstitute with bacteriostatic water and draw your dose with an insulin syringe. For intranasal use, reconstitute and transfer to a nasal spray device (see section above). The worked examples below use a 5 mg vial; the arithmetic is the same whatever size you have.

SubQ Injection — Worked Example:

Vial size in this example: 5 mg (5,000 mcg) of PE-22-28
Bacteriostatic water added: 2 mL
Concentration: 5,000 mcg ÷ 2 mL = 2,500 mcg per mL
Target dose: 200 mcg
Volume to draw: 200 ÷ 2,500 = 0.08 mL = 8 units on an insulin syringe

Quick Reference — 5 mg Vial (SubQ)

Bac Water Added	Concentration	100 mcg Dose	200 mcg Dose	300 mcg Dose
1 mL	5,000 mcg/mL	2 units (0.02 mL)	4 units (0.04 mL)	6 units (0.06 mL)
2 mL	2,500 mcg/mL	4 units (0.04 mL)	8 units (0.08 mL)	12 units (0.12 mL)
2.5 mL	2,000 mcg/mL	5 units (0.05 mL)	10 units (0.1 mL)	15 units (0.15 mL)
5 mL	1,000 mcg/mL	10 units (0.1 mL)	20 units (0.2 mL)	30 units (0.3 mL)

Skip the Math — Use Our

Enter your vial size, water volume, and desired dose — get instant calculations with zero manual math.

PE-22-28 Dosage by Goal

PE-22-28 has one mechanism, blocking TREK-1, and the goals below are different reasons people pursue that single effect. The protocols vary mostly in dose and duration rather than in anything mechanistically distinct.

Mood Support — The Primary Research Application

This is what PE-22-28 was designed for and the only application with a real preclinical literature behind it. In rodents, TREK-1 blockade produced antidepressant-like behaviour across multiple standard tests, with an onset around four days rather than the several weeks conventional antidepressants require. The proposed route is increased serotonergic activity: spadin raised the firing rate of serotonin neurons by roughly 113% in rats, an effect that disappeared when the prefrontal cortex was lesioned.

Route: Intranasal (community preference) or subcutaneous
Dose: 100–300 mcg intranasally
Frequency: 1x daily in the morning
Cycle: 4–6 weeks on, 2–4 weeks off
Critical caution: do not combine with prescribed antidepressants without medical supervision. See the safety section below.

Cognitive Support & Neuroplasticity

The downstream findings from the antidepressant research are relevant here. Spadin raised BDNF (Brain-Derived Neurotrophic Factor, a protein that supports the growth and maintenance of neurons) in the hippocampus within days, increased PSD-95 and synapsin, two markers of synapse formation, and increased the proportion of mature dendritic spines in cortical neurons. These are real results, and they follow from blocking a potassium channel rather than from any direct growth-factor signalling.

Route: Intranasal
Dose: 200–400 mcg intranasally
Frequency: 1x daily in the morning
Cycle: 4–8 weeks on, 2–4 weeks off
Stack: Pairs with Semax (100–600 mcg IN), which raises BDNF through an unrelated pathway

Neuroinflammation

TREK-1 blockade has an anti-inflammatory signal in the brain. In a rat model of major depressive disorder, spadin reduced microglial activation and inflammatory cytokine levels, and suppressed the activation of a damaging astrocyte subtype through the NF-κB pathway. This is a single rodent study rather than an established application, and it sits inside depression research rather than standing on its own.

Route: Intranasal
Dose: 200–400 mcg intranasally
Frequency: 1x daily
Cycle: 6–8 weeks on, 2–4 weeks off
Note: the supporting evidence is one animal study; treat this as the most speculative use listed here

Neuroprotection is not an established use. Older descriptions of this peptide, including the previous version of this guide, presented it as a neuroprotective compound. That came from confusing it with PACAP, and it was never based on the TREK-1 literature. What that literature actually shows is a split. Against: TREK-1’s own role includes protecting neurons, mice without the channel are more vulnerable to seizures and to ischemic brain injury, and the protective effect of polyunsaturated fatty acids vanishes in those mice. For: spadin protected cultured neurons against chemically induced cell death through a separate pathway. Different models, different endpoints, no resolution. Treat brain protection as an open question, not as a reason to buy this.

Consistency over intensity. In rodents the measurable effects appeared after about four days of consistent dosing rather than after a single large dose, which is the one thing the research does say about duration. It says nothing about the right length of a human cycle, so the multi-week protocols above remain community practice. What generalises is the shape: steady dosing rather than a short aggressive burst.

Cycling Protocols

There is no clinical data establishing optimal cycling protocols for PE-22-28. The protocols below reflect general community practice. The honest answer is that nobody knows the ideal cycle length, because no one has run a study long enough to find out.

Protocol	On-Cycle	Off-Cycle	Notes
Conservative	4 weeks	2–4 weeks off	Lowest risk; recommended for first-time users and those using higher doses
Standard	6 weeks	3–4 weeks off	Most common community protocol; the longest duration with any community track record
Extended	8 weeks	4 weeks off	Longer exposure at conservative doses; the least supported option here
5-on / 2-off (Weekly)	5 days/week	2 days off/week	Some users take weekends off to break up continuous blockade; anecdotal approach

Why Cycling Is Recommended

The usual argument for cycling a peptide is receptor downregulation, and it does not apply here. TREK-1 is an ion channel, not a G protein-coupled receptor, and it does not desensitise the way a receptor does under chronic agonist exposure.

The real argument is different and, if anything, stronger. TREK-1 has a documented protective job: mice bred without it are more susceptible to seizures and to ischemic injury in the brain and spinal cord. Holding that channel blocked continuously is therefore not a neutral state, and no study has examined what sustained blockade does over months in any species, let alone in humans. Cycling here is a precaution against an entirely unstudied chronic exposure, not a fix for a tolerance problem.

What to Use During Off-Cycles

During PE-22-28 off-cycles, users seeking continued nootropic support often switch to peptides that work through unrelated mechanisms:

Semax — works through melanocortin and TrkB pathways; raises BDNF without touching potassium channels
Selank — modulates enkephalin metabolism and GABA signalling; anxiolytic effects through an unrelated route
BPC-157 — works through the nitric oxide system, growth factor modulation, and gut-brain axis support

Cycling is precautionary, not clinically validated. There is no data showing that continuous PE-22-28 use causes a specific problem at community doses. There is also no data showing it does not. The recommendation reflects the absence of long-duration evidence for a compound that suppresses a protective channel.

PE-22-28 Stacking Protocols

PE-22-28 stacking pairs its potassium-channel mechanism with peptides that work through unrelated routes: TrkB and melanocortin signalling (Semax), enkephalin and GABA modulation (Selank), the nitric oxide system and gut-brain axis (BPC-157), and HGF/c-Met synaptogenesis (Dihexa). No combination study exists for any of these pairings. Start with PE-22-28 alone before adding stack components.

PE-22-28 + Semax — Dual-Pathway Nootropic Stack

The most popular PE-22-28 stack. Semax is a synthetic heptapeptide derived from ACTH that raises BDNF through TrkB receptor signalling and melanocortin pathways. Both peptides increase BDNF, but through entirely separate upstream mechanisms: Semax through receptor signalling, PE-22-28 as a downstream consequence of channel blockade. The theoretical case for combining them is that the two routes are independent.

Compound	Dose	Route	Purpose
PE-22-28	200–400 mcg	Intranasal, 1x daily AM	TREK-1 blockade, downstream BDNF and synaptogenesis
Semax	200–600 mcg	Intranasal, 1–2x daily	TrkB/melanocortin-mediated BDNF, cognitive enhancement

Administration note: Both PE-22-28 and Semax are administered intranasally. Space them 10–15 minutes apart to allow each peptide to absorb independently through the nasal mucosa. Administering both simultaneously may result in run-off and reduced absorption of both compounds.

PE-22-28 + Selank — Mood + Anxiolytic Stack

Selank is a synthetic heptapeptide based on tuftsin that modulates enkephalin metabolism and influences GABA signalling, producing anxiolytic effects. Where PE-22-28 increases neuronal excitability, Selank works in a broadly calming direction, which is part of why the pairing is popular: the two are not pulling on the same lever.

Compound	Dose	Route	Purpose
PE-22-28	200–300 mcg	Intranasal, 1x daily AM	TREK-1 blockade, serotonergic and BDNF effects
Selank	250–500 mcg	Intranasal, 1–2x daily	Anxiolytic via enkephalin modulation and GABA influence

PE-22-28 + BPC-157 — Mood + Gut-Brain Axis Stack

BPC-157 is a body protection compound with documented effects mediated through nitric oxide system modulation, growth factor upregulation, and gut-brain axis support. Its mechanism has no overlap with potassium channel pharmacology. BPC-157 can be administered orally or subcutaneously while PE-22-28 is used intranasally.

Compound	Dose	Route	Purpose
PE-22-28	200–400 mcg	Intranasal, 1x daily	TREK-1 blockade, BDNF and synaptogenesis
BPC-157	250–500 mcg	SubQ or oral, 1–2x daily	Nitric oxide modulation, gut-brain axis, growth factor support

PE-22-28 + Dihexa — Dual Synaptogenesis Stack

Dihexa is a synthetic hexapeptide that promotes synaptogenesis (new synapse formation) through hepatocyte growth factor (HGF)/c-Met receptor activation. PE-22-28 also increases markers of synapse formation, but arrives there from channel blockade rather than growth factor signalling. The combination targets the same endpoint from two unrelated directions.

Compound	Dose	Route	Purpose
PE-22-28	200–400 mcg	Intranasal, 1x daily	TREK-1 blockade, PSD-95 and synapsin increase
Dihexa	10–20 mg	Oral or SubQ, 1x daily	HGF/c-Met synaptogenesis, new synaptic connection formation

Stacking caution: Evidence for all PE-22-28 stacks is limited to community reports and theoretical mechanistic reasoning. No combination studies exist. Start with PE-22-28 alone for at least 2–4 weeks to establish a baseline before adding any stack components. Add one compound at a time so you can identify the source of any effects, positive or negative.

Explore more combinations with our Peptide Stack Builder or browse the Top 10 Peptide Stacks guide.

Safety, Side Effects & Contraindications

Safety Profile: Unknown. PE-22-28 has no published human safety data. What follows is community-reported effects plus what the mechanism predicts. The absence of reported serious adverse events does not confirm safety; it reflects a small user base and no systematic monitoring of any kind.

Reported Side Effects

Mild and generally self-limiting (community reports):

Nasal irritation, dryness, or mild congestion — most common with intranasal route; usually resolves with alternating nostrils and saline spray use
Mild headache — reported by some users, particularly in the first few days
Mild dizziness or lightheadedness — occasionally reported; typically transient
Transient fatigue — some users report feeling slightly tired in the first week; usually resolves with continued use
Injection site reaction — mild redness or soreness with subcutaneous administration

What Blocking TREK-1 Implies

These are not community reports, and they are not documented harms either. They are inferences from what TREK-1 does in the body, and every one of them rests on a study of a different compound, a different species, or a permanently missing channel rather than a temporarily blocked one. That is a real limitation. It is also the only safety information that exists for this peptide, and it is the reason it deserves more caution than its mild reported side effect profile suggests.

Seizure threshold — TREK-1’s normal role includes protecting the brain against seizure activity, and mice bred without the channel are more susceptible to epilepsy. Those mice lacked the channel from birth, which is not the same as blocking it in an adult, so this is an inference rather than a measured effect of PE-22-28. It is a serious enough one that anyone with a seizure history, or taking medication that lowers seizure threshold, should avoid this compound.
Heart rhythm — TREK-1 is expressed in the human heart, and inhibiting cardiac two-pore potassium channels is actively studied as an antiarrhythmic strategy, so the channel has cardiac electrophysiological relevance by design. The finding that expression is concentrated in atrial tissue comes from pigs rather than people. What a community dose of PE-22-28 does to a human heart has never been measured.
Serotonergic activity — spadin, the parent compound, increased serotonin neuron firing by roughly 113% in rats. PE-22-28 itself has not been tested this way. Combining either with serotonergic medication is an untested interaction with a plausible route to harm.
Loss of a protective channel — TREK-1 blockade removes a mechanism that protects neurons against ischemic injury, and the neuroprotective effect of polyunsaturated fatty acids disappears entirely in mice lacking the channel. Set against that, spadin protected cultured neurons from chemically induced cell death through a separate pathway. The net effect on neuronal survival in a living human is unknown, and anyone who was sold this peptide as neuroprotective was sold a claim that the literature does not make.

Contraindications

None of these are established clinical contraindications, because establishing one requires human data and none exists. They are the groups for whom the mechanism gives a specific reason for concern, which on a compound this poorly characterised is the strongest basis available.

Seizure disorder or seizure history — the clearest concern of the group. TREK-1 protects against seizure activity and this compound blocks it. Also applies to anyone taking medication known to lower seizure threshold.
Heart rhythm disorders — TREK-1 is present in cardiac tissue. Anyone with an arrhythmia, structural heart disease, or taking antiarrhythmic medication should avoid this compound.
Prescribed antidepressants or other serotonergic medication — SSRIs, SNRIs, MAOIs, tricyclics, lithium, triptans. The combination is untested and the mechanism overlaps. Speak with a prescriber first.
Pregnancy and breastfeeding — no safety data exists for PE-22-28 during pregnancy or nursing. Avoid entirely.
Any diagnosed neurological or psychiatric condition — there is no human data in any population. A compound that alters neuronal excitability and serotonergic tone is not a reasonable self-directed experiment on top of an existing diagnosis.

When to Stop or Reduce Dose

Any seizure-like symptom: an unexplained lapse in awareness, involuntary twitching or jerking, or an unfamiliar aura. Stop immediately and seek medical attention
Palpitations, a racing or irregular heartbeat, or chest discomfort. Stop and seek medical attention
Increased anxiety, agitation, restlessness, or any destabilisation of mood. A compound acting on serotonergic tone can move mood in either direction
Persistent or severe headache
Persistent nasal irritation or nosebleeds with intranasal use — switch to SubQ or take a break
Any symptom that feels unusual or concerning — with a peptide that has no human safety data, err on the side of caution

Regulatory Status: PE-22-28 is not FDA-approved for any human use. It is classified as a research peptide and is sold for research purposes only. There are no completed or ongoing human clinical trials for PE-22-28 or for spadin. Regulations vary by jurisdiction — verify your local laws before purchasing.

Common PE-22-28 Dosing Mistakes

Avoid these common errors to get the most out of your PE-22-28 protocol:

Believing this is a neuroprotective peptide: Vendor listings and secondhand write-ups frequently describe PE-22-28 as a PACAP fragment that protects the brain. It is not a PACAP fragment, and neuroprotection is not an established property. It is a spadin-derived blocker of the TREK-1 potassium channel, and TREK-1’s own documented role includes protecting neurons against seizure and ischemic injury. Buying this specifically for brain protection means paying for an effect that is unresolved at best and works against the channel’s known function at worst.

Overestimating the evidence base: Every published finding on PE-22-28 comes from rodents dosed by injection. There are no human trials, no pharmacokinetic data, and no established dose-response relationship in people. The animal work is genuinely interesting; it is not a basis for confident human dosing, and no amount of community consensus substitutes for the trials that have not happened.

Using it alongside antidepressant medication without medical supervision: In rodents, spadin raised serotonin neuron firing by roughly 113%. Stacking an untested serotonergic mechanism on top of a prescribed SSRI, SNRI, or MAOI is the single most plausible way to get hurt with this compound. This is a conversation for a prescriber, not something to work out from community protocols.

Starting at too high a dose: Because PE-22-28 is uncharacterised in humans, starting conservatively at 100–200 mcg is essential for assessing individual tolerance. Jumping to 500 mcg or higher without titrating up increases the risk of side effects and has no established benefit over lower starting doses.

Poor intranasal administration technique: Intranasal delivery requires proper technique for effective absorption. Blow your nose before administering, tilt your head slightly forward, aim the spray toward the nasal turbinates (outer wall of the nasal cavity, not the septum), and sniff gently. Do not inhale forcefully, which draws the solution past the absorptive mucosa into the throat.

Using intranasal solution that has degraded: Reconstituted PE-22-28 in nasal spray form should be kept refrigerated and used within 4–6 weeks. Peptides in solution degrade over time, especially at room temperature. Using degraded solution means unpredictable dosing and potentially inactive product. Always check for cloudiness or particulate matter before use.

Expecting dramatic acute effects: The rodent studies are notable for a fast onset by antidepressant standards, roughly 4 days rather than several weeks, but that is fast relative to medication, not fast relative to a stimulant. Nothing about the mechanism predicts an obvious acute effect, and expecting one usually leads to dose escalation that the evidence does not support.

Combining too many nootropic peptides simultaneously: Stacking PE-22-28 with Semax, Selank, Dihexa, and other nootropic peptides all at once makes it impossible to attribute effects, positive or negative, to any single compound. Start with PE-22-28 alone for at least 2–4 weeks to establish a baseline before adding complementary peptides one at a time.

Ignoring nasal health for intranasal administration: Chronic intranasal peptide use can cause nasal irritation, dryness, and mucosal damage over time. Alternate nostrils between doses, use saline spray to maintain nasal health, and take breaks from intranasal administration if irritation develops. A damaged nasal mucosa absorbs peptides inconsistently.

Storing reconstituted solution at room temperature: Peptides in solution degrade rapidly at room temperature. Reconstituted PE-22-28 must be refrigerated at 2–8°C at all times. Leaving your nasal spray bottle out on a counter, even overnight, accelerates degradation and reduces potency.

Frequently Asked Questions

Key Takeaways

PE-22-28 is a spadin-derived TREK-1 blocker, not a PACAP fragment — seven amino acids from the sortilin propeptide. Listings describing it as “PACAP(22-28)” are describing a molecule that does not exist
Its known mechanism is blocking the TREK-1 potassium channel — IC50 0.12 nM, several hundred times more potent than spadin, and longer-lasting. No broad off-target screen has been published
It is antidepressant research, not nootropic research — the literature is rodent models of depression, with a notable onset of about four days against the several weeks conventional antidepressants need
Neuroprotection is unresolved, not established — TREK-1 protects neurons against seizure and ischemic injury and this compound blocks it, while spadin protected cultured neurons from cell death by another route. The neuroprotection claim on vendor pages predates both and came from confusing PE-22-28 with PACAP
Primary route: intranasal, 100–500 mcg, 1–2x daily — community convention. No published study has ever dosed this peptide intranasally
SubQ alternative: 100–300 mcg, 1x daily — more reliable systemic absorption, and closer to the injected route the research used
Evidence base is entirely preclinical — no human trials, no pharmacokinetics, no safety data. Treat every protocol here as community practice
Start low (100–200 mcg) and titrate — with no established dose-response curve, conservative initiation is essential
Do not combine with prescribed antidepressants without supervision — spadin raised serotonin neuron firing by roughly 113% in rats; the interaction is untested
Avoid with a seizure history or a heart rhythm disorder — TREK-1 protects against seizures and is expressed in cardiac tissue. Both are inferences from the channel rather than measured effects of this peptide, and both are strong enough to act on
Cycle 4–8 weeks on, 2–4 weeks off — precautionary, because sustained blockade of a protective channel is unstudied, not because of receptor tolerance
Not FDA-approved — classified as a research peptide. Check local regulations.

This article is for educational and informational purposes only. See our Disclaimer.

References

Djillani A, et al. “Shortened Spadin Analogs Display Better TREK-1 Inhibition, Stability and Antidepressant Activity.” Front Pharmacol. 2017;8:643. PubMed
Mazella J, et al. “Spadin, a sortilin-derived peptide, targeting rodent TREK-1 channels: a new concept in the antidepressant drug design.” PLoS Biol. 2010;8(4):e1000355. PubMed
Heurteaux C, et al. “TREK-1, a K+ channel involved in neuroprotection and general anesthesia.” EMBO J. 2004;23(13):2684-2695. PubMed
Devader C, et al. “In vitro and in vivo regulation of synaptogenesis by the novel antidepressant spadin.” Br J Pharmacol. 2015;172(10):2604-2617. PubMed
Moha ou Maati H, et al. “The peptidic antidepressant spadin interacts with prefrontal 5-HT4 and mGluR2 receptors in the control of serotonergic function.” Brain Struct Funct. 2016;221(1):21-37. PubMed
Mazella J, Borsotto M, Heurteaux C. “The Involvement of Sortilin/NTSR3 in Depression as the Progenitor of Spadin and Its Role in the Membrane Expression of TREK-1.” Front Pharmacol. 2019;9:1541. PubMed
Wu F, et al. “Genetic and pharmacological inhibition of two-pore domain potassium channel TREK-1 alters depression-related behaviors and neuronal plasticity in the hippocampus in mice.” CNS Neurosci Ther. 2021;27(2):220-232. PubMed
Cong T, et al. “Blocking Two-Pore Domain Potassium Channel TREK-1 Inhibits the Activation of A1-Like Reactive Astrocyte Through the NF-κB Signaling Pathway in a Rat Model of Major Depressive Disorder.” Neurochem Res. 2023;48(6):1737-1754. PubMed
Schmidt C, et al. “Cardiac expression and atrial fibrillation-associated remodeling of K2p2.1 (TREK-1) K+ channels in a porcine model.” Life Sci. 2014;97(2):107-115. PubMed

Next Steps

Continue your research with these resources.

BPC-157 Dosage Guide

Dosing protocols for BPC-157, a peptide commonly stacked with PE-22-28 through the unrelated gut-brain axis mechanism.

Read Guide

Dosage Calculator

Calculate your exact PE-22-28 dose based on vial size and reconstitution volume.

Open Calculator

Peptide Directory

Browse all peptides with research summaries and dosing data.

View Directory