afamelanotide raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-07-28. Anything still debated is marked as such rather than presented as settled.
Melanotan-2 has not received marketing authorisation from major regulatory agencies for any therapeutic indication. Several jurisdictions classify it as a prescription-only medicine or a controlled substance when supplied for human use. Because approved products do not exist, material sold online usually sits outside pharmaceutical supply chains and formal quality oversight. Regulators have issued public notices describing the compound as unapproved. Enforcement varies, and the legal position differs between countries, which complicates any single general statement about its status.
Scientific discussion of Melanotan-2 spans pharmacology, dermatology, and public-health literature. Laboratory studies examine its receptor binding and cellular effects, while clinical reports describe outcomes observed after unregulated use. These two bodies of work differ in rigour and intent. Peer-reviewed trials of the compound as a medicine are limited, so much of the available information comes from case reports and surveillance data. Authors frequently note the gap between experimental findings and real-world use.
Reported observations after unregulated use include shifts in skin pigmentation and, in some accounts, unintended changes to moles and other lesions. Whether these outcomes are causally linked to the compound, and how often they occur, remain open questions because controlled data are scarce. The absence of standardised dosing and verified product purity complicates interpretation. Researchers have called for better surveillance and analytical characterisation of samples obtained outside regulated channels. Conclusions drawn from anecdotal evidence should be treated as provisional.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Unapproved for therapeutic use | No marketing authorisation from major agencies |
| Legal classification | Varies by jurisdiction | Prescription-only or controlled in several countries |
| Common synonyms | Melanotan II; MT-II | Also referenced by catalogue codes |
| Typical analytical method | Reverse-phase HPLC | Often paired with mass spectrometry |
| Primary literature focus | Receptor pharmacology | Pigmentation and melanocortin signalling |
Identity and purity are assessed with chromatographic and mass spectrometric techniques. Reversed-phase high-performance liquid chromatography separates the target peptide from related impurities and degradation products, and the resulting retention time is compared against a reference standard. Mass spectrometry, often coupled to liquid chromatography, confirms molecular mass. Amino acid analysis or peptide mapping can provide additional sequence-level confirmation when required. Results are only as reliable as the reference materials used alongside them.
Regulatory treatment varies by country. In the United States, melanotan-2 is not approved for any indication, and products marketed for human use fall outside the approved drug framework. Some other jurisdictions have placed it under prescription controls or listed it as a prohibited or restricted substance. Online listings frequently describe the material as a research chemical, a category that does not carry the same manufacturing and labelling requirements as approved medicines.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
Lyophilised peptide powder is comparatively stable when kept dry, cold and protected from light. Once dissolved, the molecule is exposed to hydrolysis, oxidation and microbial growth, and degradation accelerates at higher temperatures and in alkaline solution. Repeated freeze-thaw cycles concentrate solutes and promote aggregation. Handling guidance for research peptides commonly clusters around freezer temperatures for powder and short refrigerated use for reconstituted solutions, with pH control and sterile technique applied throughout.
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
Identity testing for a cyclic peptide of this size usually relies on reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The mass spectrum confirms molecular weight, while the chromatographic trace indicates the proportion of related impurities. Tandem mass spectrometry can provide sequence-level information when fragmentation data are compared against a reference standard. Nuclear magnetic resonance is sometimes used to confirm the lactam bridge, although it requires more material and greater operator expertise than routine chromatographic methods.
== Causes of reduction == An increased number of red blood cells (polycythemia) causes reduced ESR as blood viscosity increases. Hemoglobinopathy such as sickle-cell disease can have low ESR due to an improper shape of red blood cells that impairs stacking.
When two amino acids form a dipeptide through a peptide bond, it is a type of condensation reaction. In this kind of reaction, two amino acids approach each other, with the non-side chain (C1) carboxylic acid moiety of one coming near the non-side chain (N2) amino moiety of the other. One amino acid loses a hydrogen and oxygen from its carboxyl group (COOH) and the other amino acid loses a hydrogen from its amino group (NH2). This reaction produces one molecule of water (H2O), as well as two amino acids joined by a peptide bond (−CO−NH−). The two joined amino acids are called a dipeptide. The amide bond is synthesized when the carboxyl group of one amino acid molecule reacts with the amino group of the other amino acid molecule, causing the release of a molecule of water (H2O), hence the process is a dehydration synthesis chemical reaction.
==== Elimination ==== Atomoxetine and its metabolites are eliminated mainly via excretion into urine. Less than 3% of atomoxetine is excreted unchanged in urine regardless of CYP2D6 status, indicating extensive metabolism. In CYP2D6 extensive metabolizers, who are considered to have normal CYP2D6 activity, more than 96% of a dose of radiolabeled atomoxetine is excreted in urine within 24 hours and 1 to 2% is excreted in feces. Conversely, in CYP2D6 poor metabolizers, excretion is slower, with only 27% excreted after 24 hours, a majority of radioactivity excreted within 72 hours, and ~144 hours required for full excretion. In addition, only 80% of radioactivity is excreted in urine while 13 to 22% is excreted in feces in CYP2D6 poor metabolizers. The major excreted metabolite of atomoxetine is 4-hydroxyatomoxetine glucuronide, which accounts for >80% of the dose in urine but <17% of the dose in feces. The fractions excreted in urine as 4-hydroxyatomoxetine and 4-hydroxyatomoxetine glucuronide account for 86% of a dose in CYP2D6 extensive metabolizers, but only 40% in CYP2D6 poor metabolizers. CYP2D6 poor metabolizers excrete greater amounts of minor atomoxetine metabolites, namely N-desmethylatomoxetine and 2-hydroxymethylatomoxetine and their conjugates, than extensive metabolizers. The elimination half-life of atomoxetine is 4.5 to 5.3 hours in CYP2D6 extensive metabolizers. However, in CYP2D6 poor metabolizers, the half-life of atomoxetine is 19 to 21.6 hours, or about 4-fold longer in comparison.
Sources: en.wikipedia.org
The King's College Criteria or the King's College Hospital criteria were devised in 1989 to determine if there were any early indices of poor prognosis in patients with acute liver failure. Acute liver failure is defined as the onset of encephalopathy (altered mental status) or coagulopathy (altered bleeding tendencies) within 26 weeks of a patient diagnosed with liver disease. Patients with hepatitis B acquired at birth, Wilson's disease and autoimmune hepatitis are included if their disease was identified within the past 26 weeks. These patients are very ill, and have a very high risk of dying of their illness without adequate treatment which may include liver transplantation. It is important that physicians find ways of identifying patients with acute liver failure early in their course who will do poorly, and may require liver transplantation. The King's College Criteria have consistently shown excellent operating characteristics for determining prognosis in these patients. As liver transplantation becomes a more accessible option for patients with acute liver failure, the King's College Criteria serve a role in determining which patients may require transplantation.
==== Enteral/gastrointestinal route ==== Through the gastrointestinal tract is sometimes termed enteral or enteric administration (literally meaning 'through the intestines'). Enteral/enteric administration usually includes oral (through the mouth) and rectal (into the rectum) administration, in the sense that these are taken up by the intestines. However, uptake of drugs administered orally may also occur already in the stomach, and as such gastrointestinal (along the gastrointestinal tract) may be a more fitting term for this route of administration. Furthermore, some application locations often classified as enteral, such as sublingual (under the tongue) and sublabial or buccal (between the cheek and gums/gingiva), are taken up in the proximal part of the gastrointestinal tract without reaching the intestines. Strictly enteral administration (directly into the intestines) can be used for systemic administration, as well as local (sometimes termed topical), such as in a contrast enema, whereby contrast media are infused into the intestines for imaging. However, for the purposes of classification based on location of effects, the term enteral is reserved for substances with systemic effects.
In size, malonylation (three carbons) is bulkier than acetylation (two) but smaller than succinylation (four) and glutarylation (five). As a result, such acidic acyl modifications, as discussed for malonylation and succinylation, are expected to exert a greater impact than acetylation at the same lysine site. Each modification arises from the corresponding acyl-CoA derivative. Malonyl‑CoA is produced in cytosol and mitochondria by acetyl‑CoA carboxylase (ACC) and, in mitochondria, also by acyl-CoA synthetase family member 3 (ACSF3); succinyl‑CoA stems from the TCA cycle and amino acid catabolism; glutaryl‑CoA from amino acid catabolism; and methylmalonyl‑CoA from amino acid and odd‑chain fatty acid metabolism, which accumulates in vitamin B12 deficiency and methylmalonic acidemias. Malonyl‑CoA is far less reactive toward proteins than succinyl‑CoA or glutaryl‑CoA because, like acetyl‑CoA, its shorter carbon chain cannot support the intramolecular catalysis needed to form a reactive cyclic anhydride intermediate, which in turn enables modification over a broader pH range. Malonyl, succinyl, and glutaryl groups are removed by Sirtuin 5 (SIRT5), which shows little activity toward acetylation.
*Iron = ~3 g in males, ~2.3 g in females Of the 94 naturally occurring chemical elements, 76 are listed in the table above. Of the remaining 18, it is not known how many occur in the human body. Most of the elements needed for life are relatively common in the Earth's crust. Aluminium, the third most common element in the Earth's crust (after oxygen and silicon), serves no function in living cells, but is toxic in large amounts, depending on its physical and chemical forms and magnitude, duration, frequency of exposure, and how it was absorbed by the human body. Transferrins can bind aluminium.
Sources: en.wikipedia.org
=== Contract-work mods === Oct. 1997: Soldier of Fortune (Quake single player mod for Rysher Entertainment based on the television series Soldier of Fortune, Inc.) Dec. 1997: Soldier of Fortune: Deathmatch (Quake multiplayer mod for Rysher Entertainment) Apr. 1998: Soldier of Fortune: Mission 2 (Quake II single player mod for Rysher Entertainment) Jul. 1998: Coconut Monkey: Paradise Lost (Quake II single player mod for PC Gamer) Sep. 1998: Special Ops Force: Mission 3 -- Desert Bloom (Quake II single player mod for Rysher Entertainment serving as a continuation of the Soldier of Fortune series upon the renaming of the original series by Rysher) Oct. 1998: Coconut Monkey: Dry Gulch (Quake II single player mod for PC Gamer) Dec. 1998: Special Ops Force: Mission 4 -- Cold as Ice (Quake II single player mod for Rysher Entertainment) Jan. 1999: Coconut Monkey: Saving Private Monkey (Quake II single player mod for PC Gamer) Aug. 1999: USS Darkstar (Half-Life single player mod for PC Gamer) Sep. 2000: They Hunger 2: Rest in Pieces (Half-Life single player mod for PC Gamer) Nov. 2000: Vidar's Niflheim (Half-Life multiplayer TFC map for CNET Gamecenter [later updated to Vidar's Niflheim 2]) Jun. 2001: They Hunger 3: Rude Awakening (Half-Life single player mod for PC Gamer) Sep. 2003: Underworld: Bloodline (Half-Life multiplayer mod for Sony Pictures and Big Spaceship LLC based on the Underworld film series)
=== Economics === In the United States, as of 2015, the cost is between US$1,284 and US$1,386 per 30 mcg vial. As of 2020, the National Average Drug Acquisition Cost (NADAC) in the United States for Avonex was $6,872.94 for a 30 mcg kit. Avonex and Rebif are on the top ten best-selling multiple sclerosis drugs of 2013. It is an example of a specialty drug that would only be available through a specialty pharmacy. This is because it requires a refrigerated chain of distribution and costs $17,000 a year.
==== Amino acid substitution models ==== For many analyses, particularly for longer evolutionary distances, the evolution is modeled on the amino acid level. Since not all DNA substitution also alter the encoded amino acid, information is lost when looking at amino acids instead of nucleotide bases. However, several advantages speak in favor of using the amino acid information: DNA is much more inclined to show compositional bias than amino acids, not all positions in the DNA evolve at the same speed (non-synonymous mutations are less likely to become fixed in the population than synonymous ones), but probably most important, because of those fast evolving positions and the limited alphabet size (only four possible states), the DNA suffers from more back substitutions, making it difficult to accurately estimate evolutionary longer distances. Unlike the DNA models, amino acid models traditionally are empirical models. They were pioneered in the 1960s and 1970s by Dayhoff and co-workers by estimating replacement rates from protein alignments with at least 85% identity (originally with very limited data and ultimately culminating in the Dayhoff PAM model of 1978). This minimized the chances of observing multiple substitutions at a site. From the estimated rate matrix, a series of replacement probability matrices were derived, known under names such as PAM250.
Sources: en.wikipedia.org
Major regulatory agencies have not approved it for any indication. Some countries permit it only under prescription frameworks, while others classify it as a controlled substance.
Much of the evidence comes from case reports and accounts of unregulated use rather than controlled trials. Differences in product purity and dosing add further variability.
Laboratory work focuses on receptor binding and cellular signalling. Observational reports document outcomes after use, and analytical chemists examine samples to assess content and purity.
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.