Dermorphin
Dermorphin, frog skin heptapeptide mu-opioid agonist (Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2)
Written by Aaron CuhaReviewed Sep 2026
Also known as: Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2, Phyllomedusa skin opioid peptide
A seven amino acid mu-opioid agonist from South American frog skin, 30 to 40 times more potent than morphine in animals. Given to 22 people in two 1980s Italian endocrine studies and never developed as a medicine; its documented real world use is as an undetected racehorse doping agent until 2011.
Overview
Dermorphin was isolated in 1980 from the skin of Phyllomedusa tree frogs and turned out to be one of the most potent and selective mu-opioid agonists known. Its sequence, Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2, contains a D-alanine at position 2, one of the first D-amino acids found in an animal peptide, which protects it from the enzymes that would otherwise destroy it within minutes. In rodents and primates it produces intense analgesia at far lower doses than morphine and, according to the review literature, with less tolerance and dependence on chronic dosing; some family members stimulate rather than depress breathing.
What has been measured in people is small and old. In 1983, 11 healthy Italian volunteers received a 30 minute intravenous infusion of dermorphin at 5.5 mcg/kg per minute or saline in random order: prolactin rose in every subject, more in women, and the rise was abolished by naloxone, showing a mu-opioid mechanism in humans. In 1985 the same group gave it to 11 patients with prolactin secreting pituitary adenomas: prolactin did not respond, growth hormone rose in 8 of 11. Both studies used dermorphin as a probe of pituitary opioid regulation, not as a treatment. No trial of dermorphin has ever been registered on ClinicalTrials.gov and no analgesic use has been tested in a person. A 2019 commentary in Pain Medicine asks whether intrathecal dermorphin is a missed opportunity in cancer palliative care, which is a question, not a study.
Dermorphin's real world story is in horse racing. According to a 2013 analytical chemistry paper from a racing laboratory, it was misused and went undetected in North American racing until intelligence from race tracks in 2011 prompted development of a plasma and urine test, which has since been applied to official post-race samples. Pharmacokinetics were then worked out in ten research horses (elimination half-life about 45 minutes, excitation and raised heart rate after intravenous dosing), and detection methods now cover 17 dermorphin analogues in equine and human urine; a 2020 paper developing a human urine test states that human use has been reported. Dermorphin has no regulatory status anywhere and has never been submitted to a regulator.
Mechanism of action
In people, what is established comes from 22 subjects in the 1980s: intravenous dermorphin raises prolactin through a naloxone reversible, mu-opioid mechanism in healthy volunteers, and raises growth hormone in most patients with prolactinomas. That confirms it acts as a mu agonist in the human hypothalamic pituitary axis. Analgesia, respiratory effects, tolerance and dependence have never been measured in a human. In animals and cells, dermorphin binds the mu-opioid receptor with high affinity and selectivity; the D-alanine at position 2 confers resistance to aminopeptidases and the C-terminal amide to carboxypeptidases, which is why a peptide survives in blood long enough to act. It produces central antinociception after peripheral administration in rodents, meaning enough crosses the blood brain barrier to matter, and the review literature reports greater efficacy and potency than morphine with less tolerance and dependence in chronically dosed rats and mice. In horses, intravenous dosing causes transient excitation and tachycardia with an EC50 around 21 ng/mL.
Human evidence
22 people, all in Italian endocrine studies in 1983 and 1985 using dermorphin as a pituitary probe. It raised prolactin through a naloxone reversible opioid mechanism in healthy volunteers and growth hormone in prolactinoma patients. No human study has measured pain relief, breathing, tolerance or dependence.
- 1983: 11 healthy volunteers, 30 minute intravenous infusion, randomised against saline. Prolactin rose in all, abolished by naloxone.
- 1985: 11 prolactinoma patients. No prolactin response; growth hormone rose in 8 of 11.
- No analgesic trial in any human population. ClinicalTrials.gov, September 2026: zero records.
- A 2020 doping control paper reports that human use has been reported and provides a urine test; no clinical data accompany the statement.
- The 1996 review asserts analgesia in man without citing a controlled study; none could be located.
What this does not tell you: Two small studies from four decades ago establish only that dermorphin acts as a mu-opioid agonist on the human pituitary. The animal claims that make it attractive, potency far beyond morphine and less tolerance and dependence, have never been examined in a person and the experience with other opioids suggests caution about the second. Nothing is known about human respiratory depression, which for a mu agonist of this potency measured in micrograms is the finding that matters most. Nothing is known about its effect in a healthy person seeking analgesia or performance, which is the only context in which it is sold.
Reading the research record
Dermorphin is a compound with a fine animal pharmacology and no development history, and the reason is instructive. It was published in 1980 and is unpatentable as a natural product; it is a peptide and therefore injectable only; and it is a mu-opioid agonist arriving in a market that already had morphine, fentanyl and their relatives and no obvious need for a new opioid that could not be taken by mouth. The dermorphin analogue literature, some 30 compounds by 1996, was academic work on receptor selectivity, and one distant relative, the tetrapeptide [Dmt1]-DALDA, has itself since turned up in a seized unlabelled vial and in horse urine. No development programme for dermorphin is on record anywhere.
The people who did take an interest were horse trainers. Racing laboratories found dermorphin in post-race samples in 2011, and the analytical literature since then, funded by racing regulators, is the most detailed body of work on the compound. It documents pharmacokinetics in horses, detection in equine and human urine and the fact that human use has been reported, which for an opioid 30 to 40 times more potent than morphine in animals, sold as a lyophilised powder with no human dosing data, is the fact a reader should take away. The 2019 Pain Medicine commentary asking whether intrathecal dermorphin is a missed palliative care opportunity is a fair scientific question; it has not been followed by a trial.
The evidence, charted
Fig. 1 · evidence composition
3of 7 citations (43%) are in people
Counted from the citation list on this page. The Human count is the same number shown in the badge at the top. Both understate any literature larger than the sources we cite.
Fig. 2 · evidence over time
Evidence spans 7 distinct years, 1983 to 2020, counted from the citation list on this page. The newest citation on file is from 2020, more than five years ago; the published record may have gone quiet.
Fig. 3 · legal status at a glance
US
Not approved
UK
Approved
AU
Not approved
CA
Not approved
Approved in 1 of 4, prescription route in 0, not approved in 3. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Key studies & citations
- Human1983
Prolactin-releasing activity of dermorphin, a new synthetic potent opiate-like peptide, in normal human subjects
11 healthy volunteers (6 women, 5 men) given intravenous dermorphin 5.5 mcg/kg per minute for 30 minutes or saline in random order. Prolactin rose in all subjects, more consistently in women; the rise was completely suppressed by naloxone, indicating a mu-opioid mechanism. Academic study, Italy.
Journal of Clinical Endocrinology and Metabolism - Human1985
Prolactin and growth hormone responses to dermorphin in patients with prolactin-secreting pituitary adenoma
11 patients with prolactinomas (8 micro, 3 macro). No prolactin response to dermorphin in any patient; growth hormone rose in all except the 3 with macroprolactinomas. Used as an opioid probe of pituitary regulation, not as a treatment. Academic study, Italy.
Metabolism - Animal2013
Detection, quantification, and identification of dermorphin in equine plasma and urine by LC-MS/MS for doping control
States that dermorphin is 30 to 40 times more potent than morphine and was misused undetected in horse racing until 2011, when intelligence from North American tracks prompted this first detection method (limit of detection 10 pg/mL in plasma). Applied to research horses and official post-race samples. Funded by racing regulators.
Analytical and Bioanalytical Chemistry - Animal2015
Pharmacokinetics and pharmacodynamics of dermorphin in the horse
10 horses given about 9.3 mcg/kg intravenously or intramuscularly. Elimination half-life 0.76 hours intravenously; intramuscular bioavailability 47 to 100 percent; excitation and raised heart rate for about 5 minutes after intravenous dosing (EC50 21 ng/mL); detectable in urine for 48 to 72 hours.
Journal of Veterinary Pharmacology and Therapeutics - Human2020
A high throughput approach for determination of dermorphin in human urine using liquid chromatography-mass spectrometry for doping control purposes
Analytical method for dermorphin and its 1-4 metabolite in human urine, limit of detection 2.5 ng/mL, developed because, in the authors' words, use in race horses is documented and use in humans has been reported. A detection method, not a clinical study.
Journal of Mass Spectrometry - Review1996
The dermorphin peptide family
Review of seven natural dermorphins and about 30 analogues. Reports potent analgesia in rodents and primates including man, blood brain barrier penetration by some members, mu-1 selective analogues that stimulate ventilation, and less tolerance and dependence than morphine in chronically dosed rats and mice. The human analgesia statement is not referenced to a controlled trial and none could be located.
General Pharmacology - Review2005
Opioid peptide-derived analgesics
Review of analgesic development from opioid peptides including dermorphin and its analogues. Background on why peptide opioids have not reached the clinic: delivery, stability and blood brain barrier penetration.
AAPS Journal
Frequently asked questions
Has dermorphin ever been used as a painkiller in people?
Not in any published trial. The only human studies are two 1980s Italian endocrine experiments in 22 people that used it to probe pituitary hormone release. It raised prolactin by a mechanism blocked by naloxone. No study has measured pain relief, breathing, tolerance or dependence in a person.
Why is it associated with horse racing?
Racing laboratories report that dermorphin was used as an undetected doping agent in North American racing until 2011, when tips from race tracks led to a detection method. Since then it has been found in official post-race samples, its pharmacokinetics have been worked out in research horses, and tests now cover 17 related peptides in equine and human urine.
Is dermorphin less addictive than morphine?
That claim comes from chronically dosed rats and mice, as summarised in the 1996 review. It has never been tested in a human. Dermorphin is a highly selective mu-opioid agonist, and every mu agonist tested in humans has produced tolerance and dependence.
What is the danger of injecting dermorphin?
It is a mu-opioid agonist reported to be 30 to 40 times more potent than morphine in animals, dosed in micrograms, with no human dose finding data and no human data on respiratory depression, which is how opioids kill. The single human infusion study used 5.5 mcg/kg per minute under medical supervision for an endocrine measurement.