Met-enkephalin vs Endomorphin-1

Head-to-head comparison of Met-enkephalin (Tyr-Gly-Gly-Phe-Met) and Endomorphin-1 (Tyr-Pro-Trp-Phe-NH2) — benefits, dosing, side effects, research data, and where to buy.

Research Score

PropertyMet-enkephalinEndomorphin-1
CategoryPain ManagementPain Management
Full NameTyr-Gly-Gly-Phe-MetTyr-Pro-Trp-Phe-NH2
Molecular Weight573.67 Da610.71 Da
Half-Life1-5 minutes in plasmaMinutes in plasma
Amino Acids54
Typical Dose0.1-5 ug per animal0.1-10 ug per animal
RouteIntrathecal / intracerebroventricularIntrathecal / subcutaneous
Purity≥98%≥98%
Studies Count1200600
Research StatusPre-clinicalPre-clinical

Met-enkephalin Benefits

  • endogenous opioid signaling
  • analgesic reference ligand
  • spinal antinociception
  • neurochemical pain-pathway probe

Endomorphin-1 Benefits

  • mu-opioid selectivity
  • potent antinociception
  • endogenous peptide scaffold
  • useful for receptor-discovery studies

Met-enkephalin Dosing

Intrathecal 0.1-5 ug per animal|Intracerebroventricular 0.1-2 ug per animal|In vitro 1-100 nM

Endomorphin-1 Dosing

Intrathecal 0.1-10 ug per animal|Subcutaneous 0.1-5 ug per animal|In vitro 0.1-100 nM

Met-enkephalin Side Effects

  • sedation at higher exposure
  • constipation-like opioid effects
  • rapid enzymatic degradation

Endomorphin-1 Side Effects

  • respiratory depression at high exposure
  • sedation
  • tolerance and dependence potential

Research Overview

Met-enkephalin

Met-enkephalin has been extensively used in receptor pharmacology and nociception studies to map mu and delta opioid biology. The main limitation in translational work is very short half-life from peptidase cleavage and poor systemic stability.

Endomorphin-1

Endomorphin-1 is a key research peptide in studies of endogenous mu-opioid signaling and spinal analgesia. Like other peptide analgesics, its main translational hurdles are enzymatic instability, limited oral bioavailability, and delivery across barriers.

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Common Stacking Partners

Met-enkephalin stacks with:

gabapentinketamine

Endomorphin-1 stacks with:

gabapentinketamine
opioid-peptideenkephalinmu-opioidanalgesiaendogenous-peptidepain-modulation