Side-by-side · Research reference
PE 22-28vsVIP
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
BPhase 3HUMAN-REVIEWED9/42 cited
PE 22-28
TREK-1 Antagonist · Pre-Clinical
IP · SQ · Once Daily (animal models)Djillani 2017Pietri 2019
VIP
Neuropeptide · VPAC1/VPAC2 Agonist · Emergency Use Authorization (COVID-19 ARDS)
IV infusion · Inhaled (investigational)Brown 2023Boesing 2022
01Mechanism of Action
Parameter
PE 22-28
VIP
Primary target
TREK-1 two-pore-domain potassium channelDjillani 2017Ma 2020
VPAC1 and VPAC2 G-protein-coupled receptorsUdupa 2025
Pathway
TREK-1 channel blockade → Neuronal membrane depolarisation → Enhanced hippocampal excitability → Increased neuroplasticity
VIP → VPAC1/VPAC2 activation → cAMP elevation → Pulmonary vasodilation + epithelial protection
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
Anti-inflammatory cytokine modulation, alveolar-capillary membrane stabilization, pulmonary smooth muscle relaxation, reduced neutrophil infiltration
Feedback intact?
N/A — direct ion channel blockade; not receptor-mediated endocrine axis
Yes — exogenous VIP acts as physiological agonist
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
Endogenous 28-amino-acid neuropeptide; synthetic analogue (aviptadil) identical to natural VIP
Antibody development
Not reported in animal studies
—
02Dosage Protocols
Parameter
PE 22-28
VIP
Animal dose (antidepressant)
0.3–3 µg/kg IP
Effective in forced swim test, tail suspension test, CUMS models.
—
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.
—
Evidence basis
Multiple rodent RCTs; behavioral + electrophysiology endpointsDjillani 2017Qi 2018Wu 2021
Phase 3 RCT (TESICO)Brown 2023
816-patient randomized controlled trial in COVID-19 ARDS.
Intravenous (ARDS protocol)
—
60–90 mcg/kg/day via continuous infusion
TESICO trial protocol for COVID-19 ARDS.
Inhaled (investigational)
—
Variable dosing under clinical trial protocolsBoesing 2022
Delivered via nebulizer for direct pulmonary deposition.
Treatment duration
—
3–14 days (acute ARDS)
Reconstitution
—
Lyophilized powder reconstituted with sterile diluent per protocol
Half-life
—
~2 minutes (plasma)
Rapid clearance necessitates continuous infusion.
04Side Effects & Safety
Parameter
PE 22-28
VIP
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
—
Hypotension
—
Transient vasodilation-related blood pressure drop
Tachycardia
—
Reflex tachycardia secondary to vasodilation
Infusion site reactions
—
Erythema, phlebitis (IV administration)
GI symptoms
—
Nausea, diarrhea (VIP is endogenous GI peptide)
Overall tolerability
—
Well-tolerated in Phase 3 trials; adverse event profile comparable to placebo
Absolute Contraindications
PE 22-28
- ·Human use — no clinical safety data available
VIP
- ·Known hypersensitivity to aviptadil or formulation components
Relative Contraindications
PE 22-28
- ·Cardiac arrhythmia or channelopathy (theoretical TREK-1 cardiac role)
VIP
- ·Severe hypotension or shock states (monitor blood pressure)
- ·Pregnancy — insufficient safety data
05Administration Protocol
Parameter
PE 22-28
VIP
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.
Reconstitute lyophilized aviptadil powder with sterile diluent per manufacturer protocol. Inspect solution for particulates — should be clear and colorless.
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
Administer as continuous 12-hour intravenous infusion via central or peripheral line. Use infusion pump for precise dosing (60–90 mcg/kg/day divided over infusion duration).
3. BBB penetration
Enhanced CNS bioavailability vs full spadin, likely due to smaller size. Mechanism (passive diffusion vs active transport) not fully characterized.
Monitor blood pressure, heart rate, and oxygenation continuously during first infusion. Assess for hypotension and adjust infusion rate if needed.
4. Human formulation
Not established — peptide synthesis methods for research use only. No pharmaceutical-grade formulation available.
Deliver via jet or mesh nebulizer per clinical trial protocol. Patient seated upright, normal tidal breathing for 10–15 minutes.
5. Storage
—
Store lyophilized powder at 2–8 °C, light-protected. Reconstituted solution: use immediately or within 24 hours if refrigerated.