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OTHERPEPTIDE PROFILE

Deltorphin

Also known as Deltorphin I, Deltorphin II, Deltorphin A, Dermenkephalin

Deltorphin is a family of heptapeptides isolated from the skin of South American Phyllomedusa frogs. These opioid peptides show exceptional selectivity for delta-opioid receptors, with affinity several orders of magnitude greater than for mu-opioid receptors, making them invaluable research tools for studying pain modulation and opioid receptor pharmacology.

Last updated April 10, 2026

TL;DR

Quick summary

Deltorphin is a family of frog-skin heptapeptides with exceptional delta-opioid receptor selectivity, potentially offering analgesia with less respiratory depression and dependence than classical opioids.

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Overview

Deltorphin is a family of heptapeptides isolated from the skin of South American Phyllomedusa frogs. These opioid peptides show exceptional selectivity for delta-opioid receptors, with affinity several orders of magnitude greater than for mu-opioid receptors, making them invaluable research tools for studying pain modulation and opioid receptor pharmacology.

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Mechanism of action

Deltorphins bind with high selectivity to delta-opioid receptors (DOR), acting as potent agonists. Activation of DOR inhibits adenylyl cyclase via Gi/Go proteins, reduces neuronal excitability, and modulates neurotransmitter release. Unlike mu-opioid receptor agonists, delta-selective compounds may produce analgesia with reduced respiratory depression, tolerance, and physical dependence, making them subjects of interest for analgesic drug development.

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Dosing protocols

PurposeRouteDosageFrequency
receptor binding researchintravenous110 mcg/kgsingle dose per experiment

Dosing information is for educational purposes only. Consult a qualified healthcare professional before using any peptide.

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Research summary

Preclinical studies confirm Deltorphin's role as a delta-opioid receptor agonist with nanomolar affinity. Research has explored its analgesic, cardioprotective, and neuroprotective properties in rodent models. Deltorphin II has been used extensively to characterize DOR pharmacology. No human clinical trials have been conducted due to its research-only status.[1][2][3]

📄This section cites 3 peer-reviewed sources. View all references →
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Evidence grading

Each claimed benefit is graded by the strength of available evidence. Grades reflect study quality, not effect size.

strong
Nanomolar delta-opioid receptor selectivityReceptor binding pharmacology confirms orders-of-magnitude DOR selectivity vs mu and kappa
strong
Workhorse tool for DOR pharmacologyDeltorphin II widely used across receptor characterization studies as reference DOR agonist
preliminary
Potentially reduced respiratory depression vs mu-opioidsAnimal studies suggest DOR agonists spare respiratory centers; no human clinical trials conducted
preliminary
Cardioprotective in rodent ischemia modelsPreclinical myocardial ischemia-reperfusion studies suggest DOR-mediated cardioprotection
insufficient
No human clinical trials conductedResearch-only status with no clinical development toward approved indications

Strong = multiple RCTs · Moderate = limited trials or observational · Preliminary = animal or in vitro only · Insufficient = anecdotal or no published data

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Side effects

Sedation (research models)
Reduced locomotion
Respiratory effects at high doses

Side effects vary by individual. This is not an exhaustive list. Report unusual symptoms to a healthcare professional.

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Common stacks

Peptides commonly paired with Deltorphin for synergistic effects.

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Sourcing & access

Research compound

Deltorphin is classified as a research compound. Regulatory status varies by jurisdiction. Always verify current legal status and source from vendors providing third-party certificates of analysis (COA).

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Frequently asked questions

Deltorphin is a family of heptapeptides isolated from the skin of South American Phyllomedusa frogs. These opioid peptides show exceptional selectivity for delta-opioid receptors (DOR), with affinity several orders of magnitude greater than for mu-opioid receptors, making them invaluable research tools for studying opioid receptor pharmacology.

Deltorphins bind with high selectivity to delta-opioid receptors, acting as potent agonists. DOR activation inhibits adenylyl cyclase via Gi/Go proteins, reduces neuronal excitability, and modulates neurotransmitter release. Unlike mu-opioid agonists, delta-selective compounds may produce analgesia with reduced respiratory depression and tolerance.

Deltorphins are research compounds not approved for human use. In animal models, reported effects include sedation, reduced locomotion, and respiratory effects at high doses. Their delta-receptor selectivity suggests a potentially safer analgesic profile than mu-opioid agonists, but no human clinical trials have been conducted.

Deltorphin II has been used extensively to characterize DOR pharmacology. Delta-opioid receptor agonists may produce pain relief with reduced respiratory depression, tolerance, and physical dependence compared to mu-opioid drugs, making delta-selective analgesics a promising research direction for safer pain management.

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Research references

  1. Deltorphin: an opioid peptide from amphibian skin with high delta-receptor selectivityErspamer V, Melchiorri P, et al.Proc Natl Acad Sci USA, 1989PubMed
  2. Delta opioid receptor agonists: pharmacology and analgesic effectsNegri L, Lattanzi R, et al.Pharmacol Biochem Behav, 1995PubMed
  3. Delta opioid analgesics: clinical potential and receptor pharmacologyPorreca F, Mosberg HI, et al.J Pharmacol Exp Ther, 1990PubMed
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