Side-by-side · Research reference
PE 22-28vsTirzepatide
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
AAnimal-StrongHUMAN-REVIEWED16/47 cited
BFDA-ApprovedFlagship14/45 cited
PE 22-28
TREK-1 Antagonist · Pre-Clinical
IP · SQ · Once Daily (animal models)Djillani 2017Pietri 2019
Tirzepatide
GIP+GLP-1 Dual Agonist · FDA-Approved
SQ · Abdomen / thigh / arm · Once weekly
01Mechanism of Action
Parameter
PE 22-28
Tirzepatide
Primary target
TREK-1 two-pore-domain potassium channelDjillani 2017Ma 2020
GIP receptor (GIPR) + GLP-1 receptor (GLP-1R)Frias 2018
Pathway
TREK-1 channel blockade → Neuronal membrane depolarisation → Enhanced hippocampal excitability → Increased neuroplasticity
Dual GIPR/GLP-1R agonism → ↑insulin (glucose-dependent), ↓glucagon, ↓gastric emptying, ↓appetite, ↑energy expenditure (via GIP component)Jastreboff 2022Frias 2018
Downstream effect
Antidepressant-like activity in forced swim test and tail suspension test; reduced A1-like reactive astrocyte activation; neuroprotection via NF-κB pathway modulationDjillani 2017Cong 2023Wu 2021
Profound glycemic improvement and weight reduction; cardiometabolic benefitsJastreboff 2022
Feedback intact?
N/A — direct ion channel blockade; not receptor-mediated endocrine axis
Glucose-dependent insulin release preserves physiological feedback
Origin
Synthetic truncation of spadin (PE 12-28), itself derived from the sortilin propeptide C-terminus. Residues 22-28: Val-Val-Arg-Gly-Trp-Leu-Arg.Djillani 2017Mazella 2018
39-AA peptide with C-20 fatty-acid acylation. Single molecule with balanced GIP + GLP-1 affinityFrias 2018
Antibody development
Not reported in animal studies
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02Dosage Protocols
Parameter
PE 22-28
Tirzepatide
Animal dose (antidepressant)
0.3–3 µg/kg IP
Effective in forced swim test, tail suspension test, CUMS models.
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Animal dose (neuroprotection)
0.03 µg/kg IPPietri 2019
Low-dose TREK-1 activation post-stroke for 7 days, then high-dose blockade.
—
Frequency
Once daily
Sustained antidepressant effect over 7+ days.
—
Onset (animal)
Within hours (acute); full effect 4–7 days
—
Comparison to fluoxetine
PE 22-28 outperforms fluoxetine in CUMS-sensitive rats by day 7
Chronic administration shows superior long-term efficacy.
—
Human equivalent (extrapolated)
Not established — no clinical trials
Allometric scaling from rodent data unavailable.
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Evidence basis
Multiple rodent RCTs; behavioral + electrophysiology endpointsDjillani 2017Qi 2018Wu 2021
FDA-approved · Phase 3 RCTs (SURMOUNT, SURPASS)Jastreboff 2022ZEPBOUND (tirzepatide) injecti 2023
Standard dose (weight)
—
5, 10, or 15 mg / week (titrated)ZEPBOUND (tirzepatide) injecti 2023Jastreboff 2022
Titration schedule
—
2.5 mg → +2.5 mg every 4 weeks → 15 mg max
Slower titration mitigates GI side effects.
Duration
—
Indefinite for chronic indication
Reconstitution
—
Pre-filled commercial pen. Research vial: bacteriostatic water per label.
Timing
—
Once weekly, any time of day
04Side Effects & Safety
Parameter
PE 22-28
Tirzepatide
Toxicity (animal)
No adverse effects reported at therapeutic doses
—
Cardiovascular (theoretical)
TREK-1 expressed in cardiac tissue; arrhythmia risk unclear
—
Weight change
Not reported in animal studies
—
Neurological
No seizures or behavioral abnormalities noted
—
Long-term safety
Unknown — longest animal study 28 days
—
Injection site reaction
—
Mild erythema, pruritus
Thyroid C-cell tumours
—
Boxed warning — contraindicated in MEN2 / MTC historyZEPBOUND (tirzepatide) injecti 2023
Hypoglycemia
—
Low as monotherapy; risk with sulfonylureas / insulin
Gallbladder events
—
Increased cholelithiasis
Pregnancy / OB
—
Contraindicated
Diabetic retinopathy
—
Rapid glycemic improvement may transiently worsen
Absolute Contraindications
PE 22-28
- ·Human use — no clinical safety data available
Tirzepatide
- ·MTC personal or family history; MEN2
- ·Pregnancy / breastfeeding
- ·Hypersensitivity to tirzepatide
Relative Contraindications
PE 22-28
- ·Cardiac arrhythmia or channelopathy (theoretical TREK-1 cardiac role)
Tirzepatide
- ·Severe gastroparesis
- ·History of pancreatitis
- ·Diabetic retinopathy
05Administration Protocol
Parameter
PE 22-28
Tirzepatide
1. Animal protocol (IP)
Dissolved in sterile saline or vehicle. Intraperitoneal injection, 0.3–3 µg/kg body weight. Once daily administration in rodent behavioral studies.
Commercial: pre-filled pen / vial. Research lyophilised: bacteriostatic water per label.
2. Stability
Shorter peptide length (7 AA) confers improved plasma stability vs 17-AA spadin. Exact storage conditions not detailed in published protocols.Djillani 2017
SQ — abdomen, thigh, or upper arm. Rotate weekly.
3. BBB penetration
Enhanced CNS bioavailability vs full spadin, likely due to smaller size. Mechanism (passive diffusion vs active transport) not fully characterized.
Once weekly, same day. Day change allowed if ≥3 days separate doses.
4. Human formulation
Not established — peptide synthesis methods for research use only. No pharmaceutical-grade formulation available.
Refrigerate 2–8 °C unopened. Room temp ≤30 °C up to 21 days after first use.
5. Needle
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Pen-supplied. Research vial: 27–31G insulin syringe.