Dermorphin is a natural peptide (a short chain of amino acids) discovered in the early 1980s in the skin of South American frogs of the genus Phyllomedusa. It is an opioid — it acts on the same “switches” in the nervous system as morphine, only far more strongly: in tests on isolated tissues it was tens of times more potent than morphine, and in pain tests in rodents the difference reached hundreds-fold. For a few years it was studied in people, after which clinical development was abandoned; today it turns up mainly in anti-doping laboratories as a substance misused in horse racing. This review explains what dermorphin is, what the studies showed and why SWISS LAB deliberately does not offer it. For the same reason we give no doses and no methods of administration here — including those described in the studies.
What dermorphin is
Dermorphin was described in 1981 by the group of the Italian pharmacologist Vittorio Erspamer. Together with its twin, Hyp6-dermorphin, it was the first representative of “a new class of potent opioid peptides occurring in amphibian skin” (Broccardo et al., 1981). The molecule consists of seven amino acids with the sequence Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser and an amidated end. It is not a registered medicine, and its short clinical career ended in the mid-1980s.
How it works — the mu receptor and the comparison with morphine
Opioids act through opioid receptors — protein “switches” on nerve cells. For pain relief, but also for the suppression of breathing and for addiction, the most important is the mu receptor: the same one morphine acts on. Dermorphin is its agonist, that is, an “activator”. In classic tests on isolated tissues (guinea-pig ileum, mouse vas deferens) it was respectively 39 and 40 times more potent than morphine, and in pain tests in rats morphine turned out to be 752 to 2170 times less potent, depending on the test used (Broccardo et al., 1981). Naloxone — the drug used to rescue people after an opioid overdose — abolished its action, which confirms the opioid mechanism. Newer analytical papers sum it up briefly: dermorphin is “30–40 times more potent than morphine” (Guan et al., 2013).
Structure and origin — D-alanine and kambo
Dermorphin has two unusual features. Its second amino acid is D-alanine — a “mirror-image” form that vertebrate proteins practically never contain; the 1981 paper judged its presence to be “of crucial importance” for activity. The first four amino acids are also sufficient for full activity — the rest of the chain is not essential (Broccardo et al., 1981).
One simplification needs correcting. A 2018 review states that dermorphin was “traditionally called Kambo”. More precisely: kambo is the skin secretion of the frog Phyllomedusa bicolor used ritually by Amazonian peoples, and dermorphin is only one of its components — alongside phyllomedusin, phyllokinin, caerulein, sauvagine and the deltorphins, each of which acts strongly on blood vessels, the gut or stress hormones. The secretion causes nausea, vomiting, a fall in blood pressure and palpitations, and since the ritual spread beyond indigenous communities there have been “reports of severe adverse effects and deaths” (Junior and Martins, 2020). Kambo is therefore a mixture of many molecules, not dermorphin — but it shows how little is known about these peptides outside the laboratory.
What was studied — animals
Animal studies answered three questions that matter for assessing risk. First: does dermorphin cause dependence? In rats given it continuously, tolerance (a weakening of the effect) developed within at most 48 hours, and after three days naloxone precipitated a withdrawal syndrome — escape behaviour, shaking, salivation and a runny nose — “qualitatively similar” to that seen in rats made dependent on morphine (Broccardo et al., 1985). In the 1981 paper tolerance and dependence were “consistently less marked” than with morphine, but they were present.
Second: what about breathing? In anaesthetised rats a single administration of dermorphin caused apnoea, followed by slowed and deepened breathing, a fall in blood pressure and a transient slowing of the heart; cutting the vagus nerve abolished these reactions (Wojciechowski et al., 2007). In conscious rats it reduced the breathing rate and minute ventilation in proportion to the amount given, and naloxone reversed this (Paakkari et al., 1993). Third: what about sedatives? In the same study alprazolam (a benzodiazepine) potentiated the respiratory depression caused by a small amount of dermorphin, and paradoxically weakened it at a larger one.
Human data — a brief episode in the 1980s
Dermorphin was studied in people almost exclusively in Italy and only for a few years. In 11 healthy volunteers (6 women and 5 men), in random order and against placebo, it clearly raised prolactin, and when given during naloxone it did not raise it at all; this is evidence that in humans it acts through the mu receptor (Degli Uberti et al., 1983). In further volunteers it markedly and durably raised the threshold of the flexion reflex — an objective, electrically measured reaction to pain — including in a person with a complete spinal cord lesion, which points to an action at the level of the spinal cord. Naloxone reversed this effect only by about half (Sandrini et al., 1986).
The most important study was a randomised trial from 1985 in patients after surgery, in three groups: dermorphin, morphine and standard control treatment with a sham procedure (as reported in the review by Hesselink and Schatman, 2018). Dermorphin had the highest analgesic effect at every measurement: the time until the patient asked for an additional painkiller averaged 43 hours, against 34 after morphine and 11 in the control group, and additional painkillers were needed by 22% of patients against 58% and 88%. The side effects were the opioid ones — urinary retention (26% in the dermorphin group) and nausea and vomiting (22%). Then came silence: the 1985 paper was cited by only 15 pharmacological and review publications, none of them clinical, and the compound “was never again introduced in the clinical setting”.
Safety and the limits of the evidence
All the human data come from small groups, from one country, from forty years ago and from hospital conditions, after a single administration under the supervision of anaesthetists. There are no data whatsoever on longer use, on dependence in humans or on overdose — because nobody has studied them. Respiratory depression is documented in animals, and in humans it has not been studied systematically. No study is needed, though, to grasp the arithmetic: if dermorphin is tens of times more potent than morphine in tests, then a mistake in quantity weighs correspondingly more. We deliberately give no methods of use and no doses.
Doping in horses and legal status
The most recent literature on dermorphin comes not from clinics but from racing laboratories. According to a team from the University of Pennsylvania, dermorphin “was misused and went undetected in horse racing until 2011”, when intelligence from a few North American racetracks pointed to its use; the first method for detecting it in equine plasma and urine was developed then and later applied to official post-race samples (Guan et al., 2013). A year later a laboratory in Colorado noted that Racing Commissioners International had placed dermorphin in Class I — the highest category of substances banned in racehorses (Wang et al., 2014). In the current ARCI guidelines (version 18.0, March 2024) it is still listed in Class 1.
The legal status is different from what is often written. We found no official schedule in which dermorphin is listed by name as a controlled substance; it is not in the US DEA list. That does not make it legal to use in people: it is not approved as a medicine, and the rules governing trade in such substances differ between countries.
Why it is not on offer
We do not sell dermorphin and do not plan to change that. First, it is a full agonist of the mu receptor, tens of times more potent than morphine, and the consequence of a mistake in quantity is respiratory arrest — apnoea has been documented in animals (Wojciechowski et al., 2007). Second, it produces tolerance and physical dependence with a morphine-like withdrawal syndrome (Broccardo et al., 1985), which nobody has examined in humans. Third, there is no context outside a hospital in which reaching for it would make sense: the only sound human studies were conducted under the supervision of anaesthetists, forty years ago, and nobody continued them. Fourth, it is a substance in the highest class of bans in equine sport — trading in it would raise the suspicion that research is not the point. Fifth, in animals a benzodiazepine was able to intensify the suppression of breathing (Paakkari et al., 1993). For the same reasons we make an exception to our usual rule and do not even quote doses or routes of administration from the studies — for dermorphin the number itself would be an instruction.
The wider context — opioid peptides
Dermorphin belongs to the large family of opioid peptides. The human body has its own — endorphins, enkephalins, dynorphins — and the skin of Phyllomedusa frogs supplied two more groups: the dermorphins, acting on the mu receptor, and the deltorphins, acting on the delta receptor (Junior and Martins, 2020). The brain-acting peptides we describe in our knowledge base — such as Selank or Semax — are not opioids and have an entirely different risk profile.
Summary
Dermorphin is a seven-amino-acid peptide from frog skin and one of the most potent natural opioids known: tens of times stronger than morphine in tests, hundreds of times in pain tests in rodents. In rats it produces tolerance, physical dependence and respiratory depression; in humans, in a few Italian studies from the 1980s, it raised prolactin through the mu receptor, inhibited a pain reflex and, in one randomised trial after surgery, acted longer than morphine — after which clinical development stopped for good. Today it is a Class 1 substance in horse racing, not a medicine. The state of the evidence: strong pharmacological data in animals, a handful of small human studies from forty years ago and none from the present day — and the compound's potency is precisely what disqualifies it.
Sources
- Degli Uberti EC, Trasforini G, Salvadori S, et al. Prolactin-releasing activity of dermorphin, a new synthetic potent opiate-like peptide, in normal human subjects. The Journal of Clinical Endocrinology and Metabolism. 1983;56(5):1032–1034. PMID: 6833466. DOI: 10.1210/jcem-56-5-1032. pubmed.ncbi.nlm.nih.gov/6833466
- Sandrini G, Degli Uberti EC, Salvadori S, et al. Dermorphin inhibits spinal nociceptive flexion reflex in humans. Brain Research. 1986;371(2):364–367. PMID: 3697765. DOI: 10.1016/0006-8993(86)90376-8. pubmed.ncbi.nlm.nih.gov/3697765
- Hesselink JMK, Schatman ME. Rediscovery of old drugs: the forgotten case of dermorphin for postoperative pain and palliation. Journal of Pain Research. 2018;11:2991–2995. PMID: 30538538. PMCID: PMC6260176. DOI: 10.2147/JPR.S186082. pubmed.ncbi.nlm.nih.gov/30538538
- Broccardo M, Erspamer V, Falconieri Erspamer G, et al. Pharmacological data on dermorphins, a new class of potent opioid peptides from amphibian skin. British Journal of Pharmacology. 1981;73(3):625–631. PMID: 7195758. PMCID: PMC2071698. DOI: 10.1111/j.1476-5381.1981.tb16797.x. pubmed.ncbi.nlm.nih.gov/7195758
- Broccardo M, Improta G, Negri L, Melchiorri P. Tolerance and physical dependence induced by dermorphin in rats. European Journal of Pharmacology. 1985;110(1):55–61. PMID: 4040026. DOI: 10.1016/0014-2999(85)90028-7. pubmed.ncbi.nlm.nih.gov/4040026
- Wojciechowski P, Szereda-Przestaszewska M, Lipkowski AW. Supranodose vagotomy eliminates respiratory depression evoked by dermorphin in anaesthetized rats. European Journal of Pharmacology. 2007;563(1–3):209–212. PMID: 17362918. DOI: 10.1016/j.ejphar.2007.02.012. pubmed.ncbi.nlm.nih.gov/17362918
- Paakkari P, Paakkari I, Landes P, Sirén AL, Feuerstein G. Respiratory mu-opioid and benzodiazepine interactions in the unrestrained rat. Neuropharmacology. 1993;32(4):323–329. PMID: 8098861. DOI: 10.1016/0028-3908(93)90152-s. pubmed.ncbi.nlm.nih.gov/8098861
- Guan F, Uboh CE, Soma LR, et al. Detection, quantification, and identification of dermorphin in equine plasma and urine by LC-MS/MS for doping control. Analytical and Bioanalytical Chemistry. 2013;405(14):4707–4717. PMID: 23571464. DOI: 10.1007/s00216-013-6907-0. pubmed.ncbi.nlm.nih.gov/23571464
- Wang CC, Hartmann-Fischbach P, Krueger TR, et al. Fast and sensitive analysis of dermorphin and HYP6-dermorphin in equine plasma using liquid chromatography tandem mass spectrometry. Drug Testing and Analysis. 2014;6(4):342–349. PMID: 23720224. DOI: 10.1002/dta.1487. pubmed.ncbi.nlm.nih.gov/23720224
- Junior VH, Martins IA. KAMBÔ: an Amazonian enigma. Journal of Venom Research. 2020;10:13–17. PMID: 32566126. PMCID: PMC7284396. pubmed.ncbi.nlm.nih.gov/32566126
For in-vitro laboratory research only. It is not a human medicine and is not for treatment.