Side-by-side · Research reference
PE 22-28vsPT-141
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-ApprovedHUMAN-REVIEWED13/41 cited
PE 22-28
TREK-1 Antagonist · Pre-Clinical
IP · SQ · Once Daily (animal models)Djillani 2017Pietri 2019
PT-141
MC4R Agonist · FDA-Approved (HSDD)
SQ · Abdomen / thigh · ≥45 min before sex
01Mechanism of Action
Parameter
PE 22-28
PT-141
Primary target
TREK-1 two-pore-domain potassium channelDjillani 2017Ma 2020
Melanocortin-4 receptor (MC4R) in hypothalamusSimerly 2023VYLEESI (bremelanotide injecti 2019
Pathway
TREK-1 channel blockade → Neuronal membrane depolarisation → Enhanced hippocampal excitability → Increased neuroplasticity
MC4R agonism in paraventricular nucleus → autonomic + neuroendocrine sexual arousal pathwaysSimerly 2023
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
Increased sexual desire and arousal; central rather than peripheral mechanismClayton 2015
Feedback intact?
N/A — direct ion channel blockade; not receptor-mediated endocrine axis
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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
Cyclic 7-AA peptide derived from α-MSH (agonist Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-OH cyclic)VYLEESI (bremelanotide injecti 2019
Antibody development
Not reported in animal studies
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02Dosage Protocols
Parameter
PE 22-28
PT-141
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.
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Frequency
Once daily
Sustained antidepressant effect over 7+ days.
PRN, max 8 doses / month
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.
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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 (HSDD pre-menopausal women)VYLEESI (bremelanotide injecti 2019Clayton 2015
Standard dose
—
1.75 mg SQVYLEESI (bremelanotide injecti 2019
Single dose ≥45 min before anticipated sexual activity. Max 1 dose / 24 hr.
Lower / starter dose
—
1 mg (off-label)
Duration
—
PRN; reassess if no benefit after 8 doses
Reconstitution
—
Pre-filled commercial pen (Vyleesi). Research vial: bacteriostatic water.
Timing
—
≥45 min before sexual activity
04Side Effects & Safety
Parameter
PE 22-28
PT-141
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
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Neurological
No seizures or behavioral abnormalities noted
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Long-term safety
Unknown — longest animal study 28 days
—
Flushing
—
Common, transient
Injection site reaction
—
Erythema, mild pain
Headache
—
Common
Hyperpigmentation (focal)
—
Rare focal skin darkening; reversible after discontinuationVYLEESI (bremelanotide injecti 2019
Hypertension (transient)
—
Mean ↑6 mmHg systolic peaking ~4 h post-dose; resolves within 12 hVYLEESI (bremelanotide injecti 2019
Pregnancy / OB
—
Contraindicated
Cardiovascular disease
—
Use caution; transient BP rise
Absolute Contraindications
PE 22-28
- ·Human use — no clinical safety data available
PT-141
- ·Uncontrolled hypertension
- ·Known cardiovascular disease (caution)
- ·Pregnancy
Relative Contraindications
PE 22-28
- ·Cardiac arrhythmia or channelopathy (theoretical TREK-1 cardiac role)
PT-141
- ·Pre-existing hyperpigmentation disorders
- ·MC4R-pathway-dependent psychiatric conditions
05Administration Protocol
Parameter
PE 22-28
PT-141
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.
Vyleesi: pre-filled auto-injector. Research vial: 2 mL bacteriostatic water per 10 mg → 5 mg/mL.
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 or thigh.
3. BBB penetration
Enhanced CNS bioavailability vs full spadin, likely due to smaller size. Mechanism (passive diffusion vs active transport) not fully characterized.
≥45 min before sexual activity for peak effect. Effect persists ~6–8 h.
4. Human formulation
Not established — peptide synthesis methods for research use only. No pharmaceutical-grade formulation available.
Vyleesi: room temp ≤30 °C. Research vial: refrigerate after reconstitution.
5. Needle
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Auto-injector (Vyleesi) or 29–31G, 4–8 mm insulin syringe.