The short version of afamelanotide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-02-28. Anything still debated is marked as such rather than presented as settled.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Cyclic heptapeptide, C-terminally amidated |
| Approximate molecular mass | 1024 Da | Monoisotopic mass of the free peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility class | Soluble in water and polar solvents | Also dissolves in neutral aqueous buffer |
| Common synonyms | Melanotan II, MT-II, MT-2 | Described as a melanocortin agonist in early literature |
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.
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.
=== Guatemala === The Mexican Army crackdown has driven some cartels to seek a safer location for their operations across the border in Guatemala, attracted by corruption, weak policing, and its position on the overland smuggling route. The smugglers pick up drugs from small planes that land at private airstrips hidden in the Guatemalan jungle. The cargo is then moved up through Mexico to the U.S. border. Guatemala has also arrested dozens of drug suspects and torched huge cannabis and poppy fields. The U.S. government sent speedboats and night-vision goggles under a regional drug aid package. Los Zetas have gained ground in Guatemala after they killed several high-profile members and the supreme leader of Los Leones, an organized crime group from Guatemala. In February 2009, Los Zetas threatened to kill the president of Guatemala, Álvaro Colom. On March 1, 2010, Guatemala's chief of national police and the country's top anti-drugs official were arrested over alleged links to drug trafficking. A report from the Brookings Institution warns that, without proactive, timely efforts, the violence will spread throughout the Central American region. In August 2025, Guatemala granted temporary humanitarian status to 161 Mexicans fleeing cartel violence in Chiapas.
== Structure == Moroidin, a bicyclic octapeptide, has been isolated from Dendrocnide moroides (also called Laportea moroides) and Celosia argentea. The structure of moroidin was confirmed in 2004 by X-ray crystallography. It contains two unusual crosslinks, one between leucine and tryptophan and the other between tryptophan and histidine. These linkages are also present in an analogous family of compounds, the celogentins.
=== Other === Deformity type Erlenmeyer flask gives a distal femur similar to an Erlenmeyer flask. It may result from Gaucher disease. Kashin–Beck disease Melnick–Needles syndrome Ovine chondrodysplasia Familial osteodysplasia, Anderson type Ulna metaphyseal dysplasia syndrome
Approval by the US Food and Drug Administration followed in December 1993, also for use as an adjuvant (effective when added to other antiseizure drugs) medication to control partial seizures in adults; that indication was extended to children in 2000. Subsequently, gabapentin was approved in the United States for the treatment of pain from postherpetic neuralgia in 2002. A generic version of gabapentin first became available in the United States in 2004. An extended-release formulation of gabapentin for once-daily administration, under the brand name Gralise, was approved in the United States for the treatment of postherpetic neuralgia in January 2011. Gabapentin has been prescribed for a variety of disorders and is one of the more common medications used, particularly in elderly people.
== Further reading == Kwatra SG, Yosipovitch G, Legat FJ, Reich A, Paul C, Simon D, et al. (October 2023). "Phase 3 Trial of Nemolizumab in Patients with Prurigo Nodularis". The New England Journal of Medicine. 389 (17): 1579–1589. doi:10.1056/NEJMoa2301333. hdl:1854/LU-01JMVNTYQXH55FHHB47BSMETXX. PMID 37888917. Silverberg JI, Wollenberg A, Reich A, Thaçi D, Legat FJ, Papp KA, et al. (August 2024). "Nemolizumab with concomitant topical therapy in adolescents and adults with moderate-to-severe atopic dermatitis (ARCADIA 1 and ARCADIA 2): results from two replicate, double-blind, randomised controlled phase 3 trials". Lancet. 404 (10451): 445–460. doi:10.1016/S0140-6736(24)01203-0. PMID 39067461.
Sources: en.wikipedia.org
2025: Datchinamurthy Kataiah, a Malaysian drug trafficker hanged for smuggling 44.96g of diamorphine on 25 September 2025. 2025: Pannir Selvam Pranthaman, a Malaysian drug trafficker hanged on 8 October 2025 for smuggling 51.84g of diamorphine. 2026: Omar Bin Yacob Bamadhaj, a Singaporean was hanged on 16 April 2026 for trafficking 1,009.1g of cannabis in July 2018
Peter Thomas DeMarco (March 6, 1932 – October 26, 2005) was an American physician who graduated from Albright College in Pennsylvania and achieved his doctor of medicine degree in 1957 from Hahnemann Medical College of Philadelphia, Pennsylvania. He had a research laboratory and a medical practice in Pine Hill, New Jersey. He treated patients with procaine polyvinylpyrrolidone (PVP), but his medical license was suspended in New Jersey and Pennsylvania for using the unapproved therapy after an experimental permit for Procaine-PVP was withdrawn. The FDA also said his therapy might cause cancer. This was a common misconception in the 1970s. Later research revealed procaine has anti-cancer effects in human cancer cells.
== External links == GMP+synthetase at the U.S. National Library of Medicine Medical Subject Headings (MeSH) PDBe-KB provides an overview of all the structure information available in the PDB for Human GMP synthase [glutamine-hydrolyzing]
== External links == Official link San Antonio Nathan Shock Center San Antonio Claude D. Pepper Older Americans Independence Center San Antonio Center for Alzheimer's Disease and Related Dementias Population Aging and Social Studies (CAPAS) San Antonio Aging Interventions Testing Program Barshop Institute's Current Clinical Trials in Aging Research Barshop Institute's NIA T32 Biology of Aging Training Grant
Sources: en.wikipedia.org
β′ The β′ subunit is the largest subunit, and is encoded by the rpoC gene. The β′ subunit contains part of the active center responsible for RNA synthesis and contains some of the determinants for non-sequence-specific interactions with DNA and nascent RNA. It is split into two subunits in Cyanobacteria and chloroplasts. β The β subunit is the second-largest subunit, and is encoded by the rpoB gene. The β subunit contains the rest of the active center responsible for RNA synthesis and contains the rest of the determinants for non-sequence-specific interactions with DNA and nascent RNA. α (αI and αII) Two copies of the α subunit, being the third-largest subunit, are present in a molecule of RNAP: αI and αII (one and two). Each α subunit contains two domains: αNTD (N-terminal domain) and αCTD (C-terminal domain). αNTD contains determinants for assembly of RNAP. αCTD (C-terminal domain) contains determinants for interaction with promoter DNA, making non-sequence-non-specific interactions at most promoters and sequence-specific interactions at upstream-element-containing promoters, and contains determinants for interactions with regulatory factors. ω The ω subunit is the smallest subunit. The ω subunit facilitates assembly of RNAP and stabilizes assembled RNAP. In order to bind promoters, RNAP core associates with the transcription initiation factor sigma (σ) to form RNA polymerase holoenzyme. Sigma reduces the affinity of RNAP for nonspecific DNA while increasing specificity for promoters, allowing transcription to initiate at correct sites.
What Is Raynaud's Disease at the National Heart, Lung, and Blood Institute Questions and Answers About Raynaud's Phenomenon at the National Institutes of Health Bakst R, Merola JF, Franks AG, Sanchez M (October 2008). "Raynaud's Phenomenon: Pathogenesis and Management". Journal of the American Academy of Dermatology. 59 (4): 633–53. doi:10.1016/j.jaad.2008.06.004. PMID 18656283.
=== Splitting of water === The bound metal ion, plus a glutamate-histidine pair, activates and splits a water molecule from the surrounding solution. This generates a hydroxide ion within the active site.
Frequent lineup changes followed through the rest of the 1970s, and the band broke up in 1982 with Simmons the only constant member having appeared on all of their albums. In 1987, the Doobie Brothers reformed with Johnston back in the fold. McDonald, who made several guest appearances after their reformation, returned full-time in 2019. The group's sixteen studio albums include six top-ten appearances on the Billboard 200 album chart. Their 1978 album Minute by Minute reached number one for five weeks, and won a Grammy for Best Pop Vocal Performance by a Duo or Group. Their song "What a Fool Believes" from that album, written by McDonald and Kenny Loggins, won two Grammys, including Song of the Year and Record of the Year. The band had 16 Billboard Hot 100 top-40 hits, including "Listen to the Music", "Jesus Is Just Alright", "Long Train Runnin'", "China Grove", "Black Water" (#1 in 1974), "Takin' It to the Streets", "What a Fool Believes" (#1 in 1979), and "The Doctor", all of which receive rotation on classic hits radio stations. They have also released six live albums and numerous greatest hits compilations, including 1976's Best of the Doobies, certified diamond by the RIAA for reaching album sales of ten million copies. The Doobie Brothers were inducted into the Vocal Group Hall of Fame in 2004, and the Rock and Roll Hall of Fame in 2020. The group has sold more than 40 million records worldwide.
In 1963, paracetamol was added to the British Pharmacopoeia, and has gained popularity since then as an analgesic agent with few side-effects and little interaction with other pharmaceutical agents. Concerns about paracetamol's safety delayed its widespread acceptance until the 1970s, but in the 1980s, paracetamol sales exceeded those of aspirin in many countries, including the United Kingdom. This was accompanied by the commercial demise of phenacetin, blamed as the cause of analgesic nephropathy and hematological toxicity. Available in the U.S. without a prescription since 1955 (1960, according to another source), paracetamol has become a common household drug. In 1988, Sterling Winthrop was acquired by Eastman Kodak which sold the over the counter drug rights to SmithKline Beecham in 1994. In June 2009, an FDA advisory committee recommended that new restrictions be placed on paracetamol use in the United States to help protect people from the potential toxic effects. The maximum single adult dosage would be decreased from 1000 mg to 650 mg, while combinations of paracetamol and other products would be prohibited. Committee members were particularly concerned by the fact that the then-present maximum dosages of paracetamol had been shown to produce alterations in liver function.
Sources: en.wikipedia.org
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.
Afamelanotide is the linear analogue [Nle4-D-Phe7]-alpha-MSH, sometimes called melanotan I, while melanotan II is cyclic and carries three further substitutions. The two are distinct molecules and are not interchangeable in analytical testing.
Binding to the four melanocortin receptor subtypes is well documented in vitro. The relative contribution of each subtype to whole-body effects in humans is far less certain.
The dry powder is more stable during transport and storage than a solution. It also allows a known amount of material to be reconstituted at a chosen concentration.