Melanotan I

Melanotan I is a synthetic linear peptide analog of alpha-melanocyte-stimulating hormone (alpha-MSH), a naturally occurring 13-amino-acid hormone that regulates melanin production in skin melanocytes. Melanotan I carries two modifications relative to native alpha-MSH — a norleucine substitution at position 4 and a D-phenylalanine substitution at position 7 — which confer substantially greater metabolic stability and receptor binding duration than the native hormone. This modified sequence is commonly abbreviated NDP-MSH or NDP-alpha-MSH (for its developers, who worked at the University of Arizona).

At Verified Peptides, we want to be direct about an identity fact that is sometimes obscured in informal and vendor sourcing: Melanotan I is not merely 'similar to' or 'related to' afamelanotide — it is the identical molecule. Afamelanotide is the International Nonproprietary Name (INN) for this same peptide sequence, and it is marketed under the brand name Scenesse as an FDA-approved (2019) and EMA-approved (2014) subcutaneous implant for erythropoietic protoporphyria (EPP), a rare genetic photodermatosis causing severe pain on light exposure.

Chemically, Melanotan I has molecular formula C78H111N21O19, molecular weight approximately 1646.9 g/mol (independently cross-calculated from the formula, matching literature figures), CAS number 75921-69-6, PubChem CID 16164658. Melanotan I should not be confused with Melanotan II, a smaller, cyclic alpha-MSH analog with a different ring structure and a broader, less selective melanocortin-receptor activity profile, not built on this site.

We independently cross-calculated the molecular weight from the formula C78H111N21O19 (78 carbon at 12.011, 111 hydrogen at 1.008, 21 nitrogen at 14.007, 19 oxygen at 15.999), arriving at approximately 1646.9 g/mol, consistent with literature and vendor-reported figures. As a 13-residue peptide with a molecular weight well above most of the short cosmetic tripeptides and octapeptides elsewhere in this catalog, Melanotan I sits chemically closer to the larger GnRH-analog and incretin-class peptides expected later in this build phase than to the short structural peptides profiled earlier.

At Verified Peptides, we think Melanotan I stands out in this catalog for having a comparatively strong, genuinely FDA-reviewed evidence base — a rare distinction among cosmetic and gray-market research peptides. The pivotal evidence is a set of two multicenter, randomized, double-blind, placebo-controlled Phase 3 trials (Langendonk et al., New England Journal of Medicine, 2015, PMID 26132941, volume 373, issue 1, pages 48-59), conducted in the European Union (74 patients) and the United States (94 patients), testing a 16 mg subcutaneous implant administered every 60 days (five implants in the EU study, three in the US study). The trials reported an acceptable safety and adverse-event profile and a statistically significant increase in the duration of pain-free sun exposure, along with improved quality-of-life measures, in patients with erythropoietic protoporphyria, directly supporting the drug's 2019 FDA approval (as Scenesse) under orphan-drug and priority-review pathways.

We want to be direct about an important context distinction: this rigorous evidence base applies specifically to the FDA-approved subcutaneous implant formulation, administered under medical supervision as a controlled-release depot, at a defined dose and schedule, for a specific and rare medical indication. It does not directly transfer to the self-injected subcutaneous solution use that is common in unregulated 'tanning peptide' communities, where Melanotan I (and its structurally distinct relative Melanotan II) are widely used off-label for cosmetic tanning purposes without medical supervision, at doses and schedules not studied in the pivotal trials, and without the controlled pharmacokinetics of an implant. Reports of adverse effects in this unsupervised self-administration context, including nausea and flushing (both also reported in the clinical trial population, though under monitored conditions) and less common but more serious reports involving new or changing pigmented skin lesions, are a distinct safety-relevant research area from the trial data itself. We also want to note that regulatory bodies in several countries, including the UK's Medicines and Healthcare products Regulatory Agency and the US FDA, have separately issued public warnings specifically about unregulated injectable Melanotan products sold for cosmetic tanning, citing concerns including unknown product purity, unknown or incorrect dosing, non-sterile injection practices, and the pigmented-lesion monitoring concern noted above. These warnings are specifically about the unregulated cosmetic-tanning product category, not about the FDA-approved Scenesse implant used under medical supervision for erythropoietic protoporphyria, a distinction we think is easy to lose in casual secondary reporting on this compound.

At Verified Peptides, we sell research-grade Melanotan I exclusively for laboratory research, not for human self-administration, and this profile should not be read as guidance for cosmetic tanning use.

Afamelanotide's regulatory history is unusually long by peptide-drug standards: it was originally developed at the University of Arizona in the 1980s-1990s as part of research into melanocortin peptides for both tanning and skin-cancer-prevention applications, decades before its eventual 2014 EMA approval and 2019 FDA approval for erythropoietic protoporphyria — a considerably narrower and more specific indication than its original broader research intent.

Melanotan I's structural cousin, Melanotan II (a smaller, cyclic alpha-MSH analog, not built on this site), was actually the compound more directly commercialized in the unregulated 'tanning peptide' gray market, in part because Melanotan II's broader melanocortin receptor activity (including MC4R) produces additional effects, such as spontaneous erections and appetite suppression, that some users sought alongside tanning — effects less prominent with Melanotan I's somewhat more MC1R-favoring profile, though Melanotan I is also sold and used in these same unregulated contexts.

The subcutaneous implant delivery form used in the pivotal Phase 3 trials and in the approved Scenesse product is a controlled-release biodegradable matrix, a substantially different pharmacokinetic delivery approach than the immediate-release subcutaneous injection commonly used in unsupervised, non-clinical contexts — a real pharmacological distinction relevant to interpreting reported safety and efficacy data.

Erythropoietic protoporphyria itself is caused by a deficiency in ferrochelatase, the final enzyme in the heme biosynthesis pathway, leading to accumulation of protoporphyrin IX in erythrocytes, plasma, and skin. When this accumulated protoporphyrin IX absorbs visible light (rather than the ultraviolet wavelengths more commonly associated with sunburn), it generates reactive oxygen species that cause acute, severe pain, swelling, and sometimes long-term skin changes, typically within minutes of light exposure — a substantially different clinical picture from ordinary sun sensitivity, and part of why a photoprotective, pigmentation-increasing therapeutic approach was pursued for this specific rare disease.

At Verified Peptides, we require independent third-party HPLC purity testing and mass spectrometry identity confirmation for every batch of research-grade Melanotan I we offer, with a Certificate of Analysis (COA) available for each lot. As a 13-residue peptide with two non-standard amino acid substitutions (norleucine and D-phenylalanine), correct synthesis and identity confirmation of both modified positions is particularly important, since either substitution's absence would represent a different, unmodified alpha-MSH-like sequence rather than genuine Melanotan I.

We source exclusively from manufacturers operating under Good Manufacturing Practice (GMP)-aligned quality systems, and every lot is independently verified rather than accepted solely on a supplier's internal documentation. Researchers should always request and review the specific COA for the lot they receive, confirming purity percentage and molecular identity before use in any experimental protocol.

Lyophilized Melanotan I is stable when stored at -20°C, protected from light and moisture. At Verified Peptides, we ship lyophilized peptide with appropriate cold-chain packaging to preserve stability in transit.

Once reconstituted, solution should be stored refrigerated at 2–8°C and used within the timeframe indicated on the product's documentation, avoiding repeated freeze-thaw cycles. This standard reconstituted-peptide storage guidance applies to research handling of the lyophilized compound itself and is distinct from the specialized controlled-release implant formulation used in the approved clinical product, which involves proprietary manufacturing processes not replicated in standard research-grade peptide production.