Melanotan 1 vs 2: Afamelanotide, Melanotan II and PT-141 Compared

Melanotan 1 vs 2 at a glance

All three compounds in this family are analogues of alpha-melanocyte stimulating hormone (alpha-MSH), the 13-residue peptide that tells melanocytes to make eumelanin via the MC1R receptor. They were developed at the University of Arizona in the 1980s and 1990s, then went in three very different directions.

The practical difference for a researcher is receptor coverage. If the question is about pigment production at MC1R, Melanotan 1 is the cleaner tool. Melanotan II activates several receptor subtypes at once, which explains both its potency and its long list of off-target effects.

Melanotan 1: from research peptide to TGA-registered implant

Afamelanotide was taken forward by Clinuvel Pharmaceuticals, a Melbourne company, as a controlled-release implant rather than an injection. The pivotal evidence came from two randomised, placebo-controlled trials published by Langendonk and colleagues in the New England Journal of Medicine in 2015 (74 patients in Europe, 94 in the United States) in erythropoietic protoporphyria (EPP), a genetic condition that causes severe pain on sunlight exposure. In the US trial, median pain-free time in direct sunlight over six months was 69.4 hours with afamelanotide versus 40.8 hours with placebo. Adverse events were mostly mild, and serious events were not thought to be drug-related.

The TGA approved Scenesse in October 2020 for the prevention of phototoxicity in adults with EPP, the first EPP treatment registered in Australia. It is inserted by a trained health professional. That registration covers Clinuvel's implant for EPP only. It does not make research-grade Melanotan 1 a registered medicine, and it is not a tanning approval.

Melanotan II: what the only early human study found

Melanotan II was built to be more potent and more stable than Melanotan 1 by cyclising it into a seven-residue ring. The one published pilot phase I study, Dorr and colleagues (Life Sciences, 1996), gave small subcutaneous doses to healthy male volunteers over two weeks. Tanning activity appeared in the face, upper body and buttocks after only five doses. So did the effects that ended its path as a tanning drug: mild nausea at most dose levels, a stretching and yawning complex, spontaneous erections lasting one to five hours, and grade II somnolence and fatigue in one subject at the top dose.

Those erections are the reason PT-141 exists. The sexual effects of Melanotan II pointed researchers to central MC4R signalling, and bremelanotide was developed from it for that purpose. Melanotan II itself was never approved for any use in any country.

Melanotan II side effects in published case reports

Most of what is known about melanotan ii side effects comes from dermatology case reports in people who used unlicensed tanning products, not from trials. Langan and colleagues reported changing moles linked to the "sun tan jab" in the BMJ in 2009, with lesions on biopsy ranging from benign to severely dysplastic naevi. Paurobally and colleagues described melanotan-associated melanoma in the British Journal of Dermatology in 2011. Further reports describe eruptive and atypical naevi appearing within weeks of first use. Other published case reports have described priapism, rhabdomyolysis and acute kidney injury.

Two cautions apply. Case reports cannot prove causation; a 2023 UNSW explainer on the TGA warning notes that definitive proof of a melanoma link has not been established. And the products involved were of unknown content, so dose and purity were unknowable. Neither caution makes the signal reassuring: rapidly changing moles are exactly what dermatologists look for in early melanoma, and Melanotan II makes them harder to read.

Melanotan II before and after photos, injections and nasal sprays: the TGA position

The TGA has warned Australians repeatedly against melanotan tanning products. Its position, stated on tga.gov.au, is that melanotan is a prescription-only medicine, is not approved as a tanning agent, and that supplying tanning products containing it without a prescription is illegal whatever the form: injection, nasal spray, tablet or cream. These products have not been assessed for quality, safety or efficacy.

The regulator has also tested what is being sold. In a safety alert, TGA laboratory analysis of five nasal spray bottles all labelled "30 mg" found between 22 mg and 54 mg of Melanotan II per bottle, and the individual supplying them was issued 27 infringement notices. That is the problem with melanotan ii injections and melanotan ii nasal spray products sold for tanning: the label does not tell you what is inside.

Melanotan ii before and after photos on social media are the marketing arm of that trade. They show colour, not safety, not dose and not what happened to the person's moles. Our view is blunt: a before and after image is a warning sign about where a product is being sold, and none of our melanocortin peptides are for tanning or any human use.

Where PT-141 fits

Bremelanotide was approved by the US FDA in June 2019 as Vyleesi, an autoinjector for acquired, generalised hypoactive sexual desire disorder in premenopausal women. Its label shows the family resemblance: nausea in 40 percent of patients in trials, and focal hyperpigmentation of the face, gums or breasts in about 1 percent, which may not resolve after stopping. Even a compound optimised away from pigmentation still touches MC1R.

For research on central melanocortin signalling, the PT-141 research peptide is the targeted option, and the PT-141 reconstitution calculator handles lab solution maths. Researchers studying hypothalamic reproductive signalling through a different pathway often compare it with kisspeptin, which acts on the KISS1 receptor rather than any melanocortin receptor.

Choosing between them for research

For pigmentation and photoprotection models, Melanotan 1 is the better tool: one main receptor, a human evidence base, and an approved relative. Melanotan II is the right choice only when broad melanocortin activation is the point of the experiment. PT-141 sits between them for MC4R-focused work. All three are in our melanocortin peptide collection, each lot with a certificate on the COA lookup.

Shop Melanotan 1, Melanotan II and PT-141 Online for Receptor Studies

We stock all three in Australia and sell each one online. Buy Melanotan 1 as a 10 mg vial for $49 for MC1R-focused pigmentation models. Buy Melanotan II, a 10 mg vial at $49 or a 10 mL nasal spray at $59, when the experiment calls for broad melanocortin receptor activation. Buy PT-141 (bremelanotide), a 10 mg vial at $59 or a 10 mL spray at $69, for MC4R work. Each lot has an independent identity and purity certificate under the same number as the vial. Order the vial format when you need to set your own concentration, and add bacteriostatic water to the cart.

AminoBlend supplies these compounds for laboratory research only. They are not for human or veterinary use, not for tanning, and nothing here is dosing advice. Lyophilised vials are best kept cold and dark; our peptide storage guide explains why melanocortin peptides with tryptophan residues are sensitive to light and oxidation.