The short version of Melanotan II fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2025-12-25 and is reviewed periodically as new material appears.
Regulatory treatment varies by country. In the United States the peptide is not approved as a medicine, and products offered for human use may be treated as unapproved new drugs; some states also restrict sale. Australia, the United Kingdom, and European Union member states apply comparable restrictions to unapproved peptide products. Border agencies have seized shipments labelled as research chemicals. Classification may change over time, and the legal position for personal importation is not clearly settled in most published guidance.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Lyophilised storage | −20 °C, dry, protected from light | Vials are sealed and allowed to reach room temperature before opening |
| Reconstituted storage | 2 to 8 °C, protected from light | Short-term holding; avoid repeated freeze-thaw cycles |
| Reconstitution solvent | Water for injection or bacteriostatic water | Added slowly along the vial wall to reduce foaming and shear |
| Purity measurement | RP-HPLC with area normalisation | Acetonitrile-water gradient monitored at roughly 214 nm |
| Identity confirmation | Electrospray ionisation mass spectrometry | Observed mass compared against the calculated peptide mass |
Regulatory status varies by jurisdiction, and the substance is frequently described as unapproved for therapeutic use. Some authorities classify it alongside prescription-only medicines or controlled categories, while others address it through general consumer protection rules. Analytical surveys have reported mismatches between label claims and measured content in products sold online, although the scope of such testing is limited. Whether these discrepancies are widespread remains an open question. Discussion in the literature therefore tends to combine chemistry, supply-chain observation and policy analysis.
The material is commonly handled as a lyophilized powder in sealed vials. The solid dissolves readily in water and in polar organic solvents, producing a clear solution after reconstitution. Light, heat and repeated freeze-thaw cycles are the concerns most often raised in handling guidance, because peptide bonds and the constrained ring can degrade. Working solutions are generally prepared fresh, and material left in solution is treated as less stable than the dry form. These properties shape how laboratories store and aliquot reference material.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
Lyophilised melanotan-2 is comparatively robust when kept dry, cold and dark, and a desiccated powder stored at minus twenty degrees Celsius or below is generally expected to retain its chemical integrity for extended periods. In solution the peptide is far less stable, with degradation proceeding through oxidation of tryptophan and histidine residues, hydrolysis adjacent to the lactam bridge, and aggregation at higher concentrations. Repeated freeze-thaw cycling accelerates loss of the parent peak. Working aliquots are therefore prepared once, held cold, and used without letting the stock return to ambient temperature.
Quality assessment of research-grade peptide rests mainly on reversed-phase high-performance liquid chromatography for purity and on mass spectrometry for identity confirmation. A single main peak above a stated threshold, commonly ninety-eight percent by peak area, is the usual release criterion applied by suppliers. Independent analyses commissioned by laboratories and consumer organisations have repeatedly reported discrepancies between label claims and measured content, including truncated sequences, residual trifluoroacetate, and lower-than-declared peptide mass. Those findings do not establish that every supplier is unreliable, but they indicate that purity figures printed on a vial are claims requiring verification rather than settled facts.
In 2019, the FDA issued a drug safety warning about serious breathing difficulties in patients using pregabalin or gabapentin, particularly when combined with opioids or other CNS depressants. A 2022 meta-analysis found that combination therapy with opioids and gabapentinoids could be associated with an increased risk of CNS depression and mortality, and concluded that combination therapy with these medications requires close clinical monitoring. Combined use of pregabalin and alcohol produces additive impairment of cognitive and psychomotor function, as both substances act as central nervous system depressants. The pregabalin prescribing information advises against alcohol consumption during treatment, noting that the CNS depressant effects of the two substances compound one another. The combination of pregabalin and benzodiazepines produces additive CNS and respiratory depression, with pregabalin pharmacodynamically augmenting benzodiazepine sedation. A 2020 study published in the British Journal of Anaesthesia examining gabapentinoid prescribing trends in Scotland found that among recurrent gabapentinoid users, benzodiazepines were co-prescribed in 26.8% of cases, opioids in 49.9%, and both in a further 17.1%, and that the age-standardised death rate among those prescribed gabapentinoids was double that of the general Scottish population. The prescribing information for pregabalin advises monitoring for respiratory depression and sedation when co-prescribing with benzodiazepines.
Since that implies an enormous amount of Captisol is needed to stabilize and deliver remdesivir (on top of amounts needed for several other drugs for which the excipient is already in regular use), Ligand announced that it is trying to boost Captisol annual manufacturing capacity to as much as 500 metric tons. On 12 May 2020, Gilead announced that it had granted non-exclusive voluntary licenses to five generic drug companies in India and Pakistan to manufacture remdesivir for distribution to 127 countries. The agreements were structured so that the licensees can set their own prices and will not have to pay royalties to Gilead until the WHO declares an end to the COVID‑19 emergency or another medicine or vaccine is approved for COVID‑19, whichever comes first. On 23 June 2020, India granted emergency marketing approval of generic remdesivir manufactured by two Gilead licensees, Cipla and Hetero Drugs.
In the 5–10 years since 2010, there has been a change in the ways new antimicrobial agents are discovered and developed – principally via the formation of public-private funding initiatives. These include CARB-X, which focuses on nonclinical and early phase development of novel antibiotics, vaccines, rapid diagnostics; Novel Gram Negative Antibiotic (GNA-NOW), which is part of the EU's Innovative Medicines Initiative; and Replenishing and Enabling the Pipeline for Anti-infective Resistance Impact Fund (REPAIR). Later stage clinical development is supported by the AMR Action Fund, which in turn is supported by multiple investors with the aim of developing 2–4 new antimicrobial agents by 2030. The delivery of these trials is facilitated by national and international networks supported by the Clinical Research Network of the National Institute for Health and Care Research (NIHR), European Clinical Research Alliance in Infectious Diseases (ECRAID) and the recently formed ADVANCE-ID, which is a clinical research network based in Asia. The Global Antibiotic Research and Development Partnership (GARDP) is generating new evidence for global AMR threats such as neonatal sepsis, treatment of serious bacterial infections and sexually transmitted infections as well as addressing global access to new and strategically important antibacterial drugs. The discovery and development of new antimicrobial agents has been facilitated by regulatory advances, which have been principally led by the European Medicines Agency (EMA) and the Food and Drug Administration (FDA).
== See also == Climate change and infectious diseases Acanthamoeba – an amoeba that can cause amoebic keratitis and encephalitis in humans Balamuthia mandrillaris – an amoeba that is the cause of (often fatal) granulomatous amoebic meningoencephalitis Entamoeba histolytica – an amoeba that is the cause of amoebiasis, or amoebic dysentery Leptospira – a zoonotic bacteria that causes leptospirosis Methicillin-resistant Staphylococcus aureus (MRSA) Necrotizing fasciitis – the "flesh-eating disease", caused by certain types of bacteria Toxoplasma gondii – cat-carried protozoan that causes the disease toxoplasmosis Vibrio vulnificus – warm saltwater infectious bacteria
== Bioinformatics == Several bioinformatic databases exist to catalogue antimicrobial peptides. The Antimicrobial Peptide Database (APD) is the original and model database for antimicrobial peptides (https://aps.unmc.edu). Based on the APD, other databases have also been built, including ADAM (A Database of Anti-Microbial peptides), BioPD (Biologically active Peptide Database), CAMP (Collection of sequences and structures of antimicrobial peptides), DBAASP (Database of Antimicrobial Activity and Structure of Peptides), DRAMP (Data Repository of Antimicrobial Peptides)Welcome To Dramp Database, and LAMP (Linking AMPs). The Antimicrobial peptide databases may be divided into two categories on the basis of the source of peptides it contains, as specific databases and general databases. These databases have various tools for antimicrobial peptides analysis and prediction. For example, the APD has a widely used calculation interface. It also provides links to many other tools. CAMP contains AMP prediction, feature calculator, BLAST search, ClustalW, VAST, PRATT, Helical wheel etc. In addition, ADAM allows users to search or browse through AMP sequence-structure relationships. Antimicrobial peptides often encompass a wide range of categories such as antifungal, antibacterial, and antituberculosis peptides. dbAMP: Provides an online platform for exploring antimicrobial peptides with functional activities and physicochemical properties on transcriptome and proteome data.
Sources: en.wikipedia.org
== Interactions == Trimipramine should not be given with sympathomimetic agents such as epinephrine (adrenaline), ephedrine, isoprenaline, norepinephrine (noradrenaline), phenylephrine and phenylpropanolamine. Barbiturates may increase the rate of metabolism. Trimipramine should be administered with care in patients receiving therapy for hyperthyrodism.
=== Cognition === Despite some studies suggesting that sugar consumption causes hyperactivity, the quality of evidence is low and it is generally accepted within the scientific community that the notion of children's "sugar rush" is a myth. A 2019 meta-analysis found that sugar consumption does not improve mood, but can lower alertness and increase fatigue within an hour of consumption. One review of low-quality studies of children consuming high amounts of energy drinks showed association with higher rates of unhealthy behaviours, including smoking and excessive alcohol use, and with hyperactivity and insomnia, although such effects could not be specifically attributed to sugar over other components of those drinks such as caffeine.
31 August – More than 100 schools in England are told to close buildings while work is carried out on concrete prone to collapse. Thousands of pupils will face being taught via remote learning or in temporary classrooms while the work is completed. After junior doctors in England vote to continue strike action, the British Medical Association announces that junior doctors and consultants will stage co-ordinated strikes going forward. Police in Pakistan say they did not receive an Interpol request to search for the family of Sara Sharif until 15 August, five days after her body was found at a house in Woking, Surrey.
== Case study == In 1988, Summons et al. studied the Proterozoic Kwagunt Formation of the Chuar Group in Grand Canyon, Arizona. This sedimentary rock is 850 million years old. After performing an extraction of the rocks with organic solvents, Summons characterized the abundance of various lipid biomarkers using GC-MS/MS, as described above. Using the 412-->191 m/z transition, they identified gammacerane in the extract. Summons interpreted this signal as the diagenetic product of tetrahymanol. At the time, this lipid had only been observed in protozoa, mainly ciliates. They interpreted it as a biomarker for the existence of protozoa in the Neoproterozoic. This report is still the oldest observation of gammacerane in the rock record.
Originally, the term radiation protection referred only to ionizing radiation. Today, non-ionizing radiation is also included and is the responsibility of the Federal Office for Radiation Protection, the Radiation Protection Division of the Federal Office of Public Health and the Ministry of Climate Action and Energy (Austria). The project collected, evaluated and compared data on the legal situation in all European countries (47 countries plus Germany) and major non-European countries (China, India, Australia, Japan, Canada, New Zealand and the USA) regarding electric, magnetic and electromagnetic fields (EMF) and optical radiation (OS). The results were very different and in some cases deviated from the recommendations of the International Commission on Non-Ionizing Radiation Protection (ICNIRP).
Sources: en.wikipedia.org
Low temperature slows hydrolysis and oxidation, the two main routes by which the peptide backbone and side chains are modified. A lyophilised powder stored at −20 °C is more stable than one kept at room temperature, and once the material is dissolved the degradation rate rises, making refrigeration more important.
Liquid chromatography coupled to mass spectrometry is the most common approach because it combines a retention time with a mass measurement. A chromatographic peak alone cannot establish which peptide is present, so mass determination or amino acid analysis is used as an orthogonal confirmation alongside the separation.
This depends on buffer, pH, and concentration, and published stability data for this peptide are limited. In practice laboratories work through a refrigerated solution within a few weeks and discard samples that show cloudiness or visible particles. Freezing and thawing repeatedly is generally discouraged.
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.