Dermorphin: the frog opioid peptide, its potency and its doping history

Dermorphin is a natural opioid peptide from a frog, and the dermorphin frog origin is not a curiosity but the reason it exists in this form. In 1980 researchers examining methanol extracts of the skin of Phyllomedusa frogs from South America found peptides with powerful opiate-like activity, and in 1981 Pier Carlo Montecucchi, Vittorio Erspamer and colleagues published the amino acid sequence of the one they named dermorphin, isolated from Phyllomedusa sauvagei: H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2 ^[1]. A companion paper reported dermorphin and Hyp6-dermorphin from the skin of Phyllomedusa rhodei ^[2].

The striking feature is the second residue. Dermorphin contains D-alanine, a D-amino acid, which was a genuine surprise in a peptide from a vertebrate, since animal proteins are built almost entirely from L-amino acids ^[1]. That D residue is not decoration: it is what gives the peptide both its resistance to breakdown and its receptor selectivity. The frogs make it through an unusual route in which the gene encodes an L-amino acid precursor that is enzymatically converted afterwards; a 1990 study reported that the same skin precursors encoding deltorphins also carry the genetic information for three dermorphin-related opioid peptides ^[3].

By 1996 the family had grown to seven naturally occurring peptides and nearly thirty synthetic analogues, reviewed by Melchiorri and Negri, who described dermorphins as potent analgesics in rodents and primates including humans, some of which cross the blood-brain barrier and produce central pain relief after peripheral dosing ^[4]. This is the essential point about dermorphin, and it separates it from everything else on this site: dermorphin opioid activity is the whole of what it does. Our guide to what research peptides are covers the research-use label generally, but that label does not change what this molecule does. Dermorphin is sold by some of the same stores that sell recovery peptides such as BPC-157 and sleep-related peptides such as DSIP, and it does not belong in the same conversation as either.

The dermorphin mu opioid receptor interaction is the whole of its pharmacology. Dermorphin binds mu-opioid receptors, the same receptors morphine, fentanyl and heroin act on, with high affinity and unusual selectivity. A 1992 study reported that dermorphin-related peptides from Phyllomedusa bicolor skin, and their amidated analogues, activate two mu-opioid receptor subtypes that separately modulate pain relief and catalepsy in the rat ^[5]. That division, mu1 for analgesia and a different population for the rigidity and immobility seen at higher doses, runs through the pharmacology.

The potency figures quoted for dermorphin are large. The dermorphin vs morphine comparison is made directly in the analytical literature: a 2013 doping-control paper from the University of Pennsylvania’s equine toxicology laboratory describes dermorphin plainly as 30 to 40 times more potent than morphine ^[6]. Potency here means the dose needed for a given effect, not safety: a more potent opioid is not a safer one, it is one where the gap between an active amount and an excessive amount is measured in smaller numbers.

The respiratory pharmacology is genuinely unusual and often misreported. In awake rats, analgesic doses of [Lys7]dermorphin increased respiratory frequency and minute volume rather than depressing them, an effect blocked by naloxone and reduced by a mu1-selective antagonist; but higher, cataleptic doses reduced breathing and blocked the normal ventilatory response to carbon dioxide, and the peptide’s main metabolites never stimulated breathing and reduced ventilation at every dose tested ^[7]. In other words, the stimulation is dose-limited and the breakdown products are not. Nobody should read a rat study reporting respiratory stimulation as evidence that a potent opioid peptide is unlikely to suppress breathing in a person.

The animal literature on dermorphin is large and consistent: it produces strong antinociception, that is, reduced response to painful stimuli, across routes and species. Peripheral administration of [Lys7]dermorphin produced antinociception in rats ^[8], glycosylated dermorphin analogues were developed specifically to improve activity after systemic dosing ^[9], and dermorphin interacts with delta-opioid agonists in supraspinal pain modulation ^[10].

It also does the other things opioids do. It slows the gut: dermorphin affected gastrointestinal transit in rats ^[11] and inhibited gastric emptying through a pituitary-adrenal mechanism ^[12]. It raises prolactin: a 1984 rat study found dermorphin stimulated prolactin secretion ^[13]. And, importantly, it produces tolerance and dependence. In a 1985 study, rats receiving continuous dermorphin infusion into the lateral ventricle developed tolerance to analgesia, catalepsy and rigidity within 48 hours, and after three days of infusion a naloxone injection precipitated a withdrawal syndrome with escape behaviour, shaking, salivation and rhinorrhoea, qualitatively similar to morphine withdrawal ^[14]. A companion study found cross-tolerance between dermorphin and morphine ^[15].

The 1996 review argues that dermorphins have higher antinociceptive efficacy and potency than morphine and may be less likely than morphine to produce tolerance, dependence and opiate side effects ^[4]. That is a claim about relative risk between opioids made in rodents, and the 1985 dependence study from the same research group shows that less likely does not mean unlikely ^[14].

Dermorphin has been given to people, but only in small physiology experiments in the early 1980s, and never in a clinical development programme.

In 1983, eleven healthy volunteers, six women and five men, received a synthetic dermorphin infusion of 5.5 µg per kg per minute for 30 minutes, or saline, in random order. Dermorphin significantly raised prolactin levels, more consistently in women than in men, and the response was completely suppressed by naloxone, confirming that it acted through mu-opioid receptors ^[16].

In 1986, a study reported that intravenous dermorphin at 0.16 mg/kg produced a marked and long-lasting increase in the threshold of the nociceptive flexion reflex in healthy volunteers, an objective measure of spinal pain processing. The effect was also present in a person with a complete chronic spinal cord injury, indicating a mainly spinal site of action, and naloxone reversed only about half of it, which the authors suggested meant dermorphin engages more than one spinal opioid receptor population ^[17].

That is the entire published human record as far as our searches found: two studies, fewer than twenty participants in total, measuring hormone release and a reflex threshold. No trial has assessed dermorphin for pain management, no trial has assessed its safety over more than a single dose, and there is no modern human pharmacokinetic study. A 2019 commentary in Pain Medicine raised the question of whether dermorphin represents a missed opportunity for intrathecal therapy in palliative care ^[18], which is a proposal for research rather than a report of it.

The dermorphin horse racing story is the reason most laboratories work on the peptide today. It was misused in horse racing and went undetected until 2011, when intelligence from North American racetracks prompted the development of analytical methods, and the first liquid chromatography tandem mass spectrometry method for detecting it in post-race horse samples was published in 2013 ^[6]. A parallel method from an Australian racing laboratory screened for seventeen dermorphin peptides in equine urine and plasma with detection limits down to 5 pg/mL, and noted that the same extraction technique works for human urine ^[19].

A 2015 study in the horse established the pharmacology directly: ten horses received dermorphin at about 9.3 µg/kg intravenously or intramuscularly. The elimination half-life was roughly 0.76 hours after intravenous dosing and 0.68 hours after intramuscular dosing, intramuscular bioavailability was variable at 47 to 100 per cent, and only about 5 per cent of the dose appeared in urine. Intravenous dosing produced excitation and a raised heart rate that subsided within five minutes. Dermorphin was detectable in plasma for 12 hours and in urine for 48 to 72 hours ^[20].

The detection effort has continued and broadened. A 2020 method was published specifically for determining dermorphin in human urine for doping control purposes ^[21], and in 2024 a Hong Kong racing laboratory reported identifying the dermorphin tetrapeptide analogue [Dmt1]-DALDA in a seized unlabelled vial and detecting it in horse urine for the first time ^[22]. That last case is the most directly relevant to anyone buying peptides online: an unlabelled vial seized from circulation turned out to contain a potent synthetic opioid analogue.

There is no published dermorphin half life measured in people, and the animal figures are short. In the human flexion reflex study, intravenous dermorphin produced a marked and long-lasting rise in the pain threshold ^[17], and in the prolactin study the hormone response followed a 30-minute infusion ^[16]. In horses, effects on heart rate appeared immediately after intravenous dosing and subsided within five minutes, while the peptide itself had an elimination half-life of under an hour ^[20].

The short half-life relative to the duration of effect is a known feature of opioid peptides and is not reassuring: a compound whose effects outlast its measurable presence is harder to titrate, not easier.

No dermorphin dosage has been established for any medical use. The following records what published studies administered, in supervised laboratory settings, decades ago. These are not recommendations, and this site does not recommend any dose of an opioid. The 1983 human study infused 5.5 µg per kg per minute for 30 minutes intravenously ^[16]. The 1986 human study used a single intravenous dose of 0.16 mg/kg ^[17]. The horse pharmacokinetic study used about 9.3 µg/kg intravenously or intramuscularly ^[20]. Rodent work used intracerebroventricular and subcutaneous dosing across wide ranges, with analgesic and cataleptic dose bands that differ by roughly two orders of magnitude ^[7].

The gap between those numbers is the point. In the rat respiratory study, doses producing antinociception stimulated breathing, and doses producing catalepsy suppressed it and blocked the response to carbon dioxide ^[7]. With an opioid 30 to 40 times more potent than morphine ^[6], measuring error and reconstitution error translate directly into that dose gap. Our peptide calculator and the dermorphin calculator page will convert vial contents into concentrations, and being able to do the arithmetic accurately does not make self-administering a potent opioid peptide a reasonable thing to do.

Published administration has been intravenous in humans ^{[16] [17]}, intravenous and intramuscular in horses ^[20], and intracerebroventricular, subcutaneous and intraperitoneal in rodents ^{[7] [8] [14]}. Suppliers sell dermorphin as a lyophilised powder. Some members of the family cross the blood-brain barrier after peripheral administration and some do not, and the analytical literature notes that dermorphins have limited ability to cross it, producing effects on both the central and peripheral nervous systems ^[19] — a nuance that varies by analogue and is not settled for any given vial.

A specific caution about naming. Dermorphin, [Lys7]dermorphin, Hyp6-dermorphin, [DPro6]dermorphin and [Dmt1]-DALDA are different molecules with different potencies ^{[2] [4] [22]}. Racing laboratories screen for seventeen of them at once because sellers do not distinguish carefully ^[19]. A vial labelled dermorphin cannot be assumed to contain the natural heptapeptide sequence.

Dermorphin is an opioid, and the risks are opioid risks. The published animal literature documents tolerance developing within 48 hours of continuous dosing and a naloxone-precipitated withdrawal syndrome after three days, qualitatively like morphine withdrawal ^[14], and cross-tolerance with morphine ^[15]. It causes catalepsy and rigidity at higher doses ^[5], slows gastrointestinal transit and gastric emptying ^{[11] [12]}, and raises prolactin in both rats and people ^{[13] [16]}.

Respiratory depression is the risk that kills people who use opioids, and the dermorphin data on it are mixed in a way that should increase caution rather than reduce it: analgesic doses stimulated breathing in awake rats, cataleptic doses depressed it and blocked the carbon dioxide response, and the peptide’s main metabolites depressed ventilation at all doses tested ^[7]. Nobody has studied what happens when dermorphin is combined with alcohol, benzodiazepines, gabapentinoids or other opioids, which is the combination behind most opioid deaths.

There are no modern human safety data of any kind. The two human studies were single-dose physiology experiments run under supervision in a hospital setting in the 1980s ^{[16] [17]}, with naloxone available. Nothing is known about repeated use, addiction liability in humans, overdose thresholds, effects in pregnancy or interactions. Dermorphin also has abuse and dependence potential by its pharmacology, and possession or supply of opioid substances is controlled in most of the countries we cover regardless of how a vial is labelled.

Dermorphin is not an approved medicine anywhere we are aware of and has no clinical development programme. Because it is a potent mu-opioid agonist, it is likely to fall under controlled-drug legislation in many jurisdictions irrespective of its research-chemical labelling, and analogue provisions in several countries are written to capture exactly this situation. We are not able to give a definitive answer for every country, and anyone considering buying it should establish the position where they live before doing anything else. See our legal status overview and the pages for the UK, the US and Canada, and note that the peptide-specific framework described in our report on the FDA advisory committee meeting on compounded peptides is not the framework that governs opioids.

In sport, opioids are prohibited in competition under the standard anti-doping codes and dermorphin has a documented misuse history in horse racing ^{[6] [19] [22]}. Validated methods exist for detecting it and its analogues in both equine and human urine ^{[19] [21]}. Anyone subject to testing should treat it as a prohibited substance and check the current list themselves.

Dermorphin is supplied as a freeze-dried powder. Peptides are generally kept cold, dry and away from light, and reconstituted solutions refrigerated. See how to store peptides and bacteriostatic water. One analytical detail is worth knowing: the doping-control literature reports that dermorphin in plasma is stable at ambient temperature but that its diastereomer, the form with the wrong stereochemistry at the D-alanine, is not ^[6]. Stereochemistry is the whole design of this molecule, and it is the one thing an ordinary mass measurement cannot check.

We track listings and prices because people search for them, and this is a page where the honest advice is different from the usual one. Dermorphin is a potent opioid with an abuse and doping history, no modern human safety data, and documented tolerance and dependence in animals. There is no research-use framing that makes self-administration of it a sensible idea, and pain management is a matter for a doctor.

If you are researching the market regardless: compare dermorphin prices, including listings in the UK and the US. A certificate of analysis should show a measured mass close to 802.9 g/mol for the natural heptapeptide, and should state the sequence, because the family contains many analogues of differing potency ^{[4] [22]}. Our guides to how to read a peptide COA, third-party peptide testing and how to spot a fake peptide supplier explain what the paperwork should contain, the stores publishing independent results are listed under third-party tested suppliers, and peptide prices explained covers why prices vary. The 2024 seized-vial case, in which an unlabelled vial turned out to contain a potent dermorphin analogue ^[22], is the clearest illustration of what an unverified label is worth.