Side-by-side · Research reference
LiraglutidevsPE 22-28
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
AFDA-ApprovedFlagship14/45 cited
BAnimal-StrongHUMAN-REVIEWED16/47 cited
Liraglutide
Daily GLP-1 RA · FDA-Approved
SQ · Abdomen / thigh / arm · Once daily
PE 22-28
TREK-1 Antagonist · Pre-Clinical
IP · SQ · Once Daily (animal models)Djillani 2017Pietri 2019
01Mechanism of Action
Parameter
Liraglutide
PE 22-28
Primary target
GLP-1 receptor (GLP-1R)SAXENDA (liraglutide) injectio 2014
TREK-1 two-pore-domain potassium channelDjillani 2017Ma 2020
Pathway
GLP-1R agonism → ↑glucose-dependent insulin, ↓glucagon, ↓gastric emptying, ↓appetiteSAXENDA (liraglutide) injectio 2014Marso 2016
TREK-1 channel blockade → Neuronal membrane depolarisation → Enhanced hippocampal excitability → Increased neuroplasticity
Downstream effect
Glycemic improvement, modest body-weight reduction, cardiovascular event reduction in high-risk T2DMarso 2016
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
Feedback intact?
Glucose-dependent insulin release preserves physiological feedback
N/A — direct ion channel blockade; not receptor-mediated endocrine axis
Origin
Modified GLP-1(7-37) with Lys26 substitution (Arg34) and C-16 palmitoyl-glutamate acylation for albumin bindingSAXENDA (liraglutide) injectio 2014
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
Antibody development
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Not reported in animal studies
02Dosage Protocols
Parameter
Liraglutide
PE 22-28
Standard dose (weight, Saxenda)
3.0 mg / day (after 5-week titration)SAXENDA (liraglutide) injectio 2014
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Frequency
Once daily, same time each day
Once daily
Sustained antidepressant effect over 7+ days.
Titration schedule
0.6 → 1.2 → 1.8 → 2.4 → 3.0 mg over 5 weeks
Mitigates GI side effects.
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Evidence basis
FDA-approved · Phase 3 RCTs (LEADER, SCALE)Marso 2016SAXENDA (liraglutide) injectio 2014
Multiple rodent RCTs; behavioral + electrophysiology endpointsDjillani 2017Qi 2018Wu 2021
Duration
Indefinite for chronic indication
—
Reconstitution
Pre-filled commercial pen (no reconstitution)
—
Timing
Any time of day; consistent
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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.
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.
04Side Effects & Safety
Parameter
Liraglutide
PE 22-28
GI symptoms
Nausea, vomiting, diarrhea (very common during titration)SAXENDA (liraglutide) injectio 2014
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Pancreatitis risk
Rare; discontinue if suspected
—
Thyroid C-cell tumours
Boxed warning — contraindicated in MEN2 / MTC historySAXENDA (liraglutide) injectio 2014
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Hypoglycemia
Low risk as monotherapy; elevated with sulfonylureas / insulin
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Heart rate
Modest ↑ resting HR (~2-3 bpm)
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Pregnancy / OB
Contraindicated
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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
Absolute Contraindications
Liraglutide
- ·MTC personal or family history; MEN2
- ·Pregnancy / breastfeeding
- ·Hypersensitivity to liraglutide
PE 22-28
- ·Human use — no clinical safety data available
Relative Contraindications
Liraglutide
- ·Severe gastroparesis
- ·History of pancreatitis
- ·Severe gastrointestinal disease
PE 22-28
- ·Cardiac arrhythmia or channelopathy (theoretical TREK-1 cardiac role)
05Administration Protocol
Parameter
Liraglutide
PE 22-28
1. Reconstitution / device
Commercial pre-filled pen, no reconstitution required.
Dissolved in sterile saline or vehicle. Intraperitoneal injection, 0.3–3 µg/kg body weight. Once daily administration in rodent behavioral studies.
2. Injection site
SQ — abdomen, thigh, or upper arm. Rotate sites.
Shorter peptide length (7 AA) confers improved plasma stability vs 17-AA spadin. Exact storage conditions not detailed in published protocols.Djillani 2017
3. Timing
Once daily, same time each day. Take with or without food.
Enhanced CNS bioavailability vs full spadin, likely due to smaller size. Mechanism (passive diffusion vs active transport) not fully characterized.
4. Storage
Refrigerate 2–8 °C unopened; room temp ≤30 °C up to 30 days after first use.
Not established — peptide synthesis methods for research use only. No pharmaceutical-grade formulation available.
5. Needle
Pen-supplied 32G needle.
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