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Endomorphin-1
Overview
Endomorphin-1 is a tetrapeptide (Tyr-Pro-Trp-Phe) that exhibits highly selective agonist activity at the mu-opioid receptor, the primary target for analgesic opioids. It is one of two endomorphin isoforms and represents the most selective endogenous mu-opioid ligand identified to date.
Mechanism of Action
Endomorphin-1 is distributed in pain-processing regions of the central nervous system. Its selective mu receptor activity theoretically offers potent analgesia with a potentially different side effect profile compared to less selective opioids.
Research Summary & Key Findings
Preclinical studies have shown that endomorphin-1 produces potent analgesia in rodent models when administered intrathecally or intracerebroventricularly. Challenges including poor metabolic stability, limited blood-brain barrier penetration, and rapid enzymatic degradation have prevented clinical development. Research efforts have focused on designing stabilized analogs and prodrug strategies to improve pharmacokinetic properties.
Clinical Status
Endomorphin-1 is in the research phase with limited clinical data in humans. Current evidence is primarily derived from preclinical (animal or in vitro) studies.
Administration Routes
References
Primary literature
- PubMed: "Endomorphin-1"
Peer-reviewed literature indexed by the National Library of Medicine.
- ClinicalTrials.gov: "Endomorphin-1"
Registered interventional and observational studies, including status and phase.
- PubChem: "Endomorphin-1"
Chemical structure, molecular properties, and bioactivity data.
Study-level citations for this compound are being verified against the primary sources before publication. The database queries above return the current indexed literature in the meantime.
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View detailsNo lawful pathway today
Endomorphin-1 is not FDA-approved and does not currently have a lawful prescription or compounding pathway in the United States, so there is nothing for us to sell you here and no consultation to book. That can change: eight peptides moved back to a lawful pathway in February 2026.
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List Your PracticeDisclaimer: This information is provided for educational and research purposes only. It is not intended as medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before starting any peptide therapy. The Peptide Association does not endorse or recommend any specific treatment protocol. See our editorial policy for how this content is produced and reviewed.