Nociceptin vs Met-enkephalin

Head-to-head comparison of Nociceptin (Nociceptin/orphanin FQ) and Met-enkephalin (Tyr-Gly-Gly-Phe-Met) — benefits, dosing, side effects, research data, and where to buy.

Research Score

PropertyNociceptinMet-enkephalin
CategoryPain ManagementPain Management
Full NameNociceptin/orphanin FQTyr-Gly-Gly-Phe-Met
Molecular Weight1881.1 Da573.67 Da
Half-Life~minutes1-5 minutes in plasma
Amino Acids175
Typical Doseno approved human dose|research-only0.1-5 ug per animal
Routeintrathecal|intranasalIntrathecal / intracerebroventricular
Purity≥98%≥98%
Studies Count441200
Research StatusPre-clinicalPre-clinical

Nociceptin Benefits

  • allodynia reduction
  • central pain modulation
  • neuropathic pain research

Met-enkephalin Benefits

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

Nociceptin Dosing

no established human dose|research-only dosing varies

Met-enkephalin Dosing

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

Nociceptin Side Effects

  • sedation
  • dysphoria

Met-enkephalin Side Effects

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

Research Overview

Nociceptin

Nociceptin is a major pain-pathway peptide in the spinal cord, brainstem, and trigeminal system. Its relevance to migraine and neuropathic pain is mainly preclinical, where receptor-selective tools are being explored.

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.

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Common Stacking Partners

Nociceptin stacks with:

Orphanin FQOFQ

Met-enkephalin stacks with:

gabapentinketamine
neuropathic-paintrigeminal-painopioid-likeopioid-peptideenkephalinmu-opioidanalgesia