Melanotan I (afamelanotide) and Melanotan II are both synthetic analogues of alpha-melanocyte-stimulating hormone (α-MSH), a naturally occurring melanocortin peptide. Research describes both as agonists at melanocortin receptors (MCRs). They differ in receptor selectivity, structure, research history, and regulatory status. The near-identical names cause constant confusion, but only one has reached approved therapeutic status anywhere. Melanotan II is not approved for human use in any jurisdiction. It is sold for research use only and is not approved for human consumption.
Melanocortin Receptors: The Selectivity Difference
The melanocortin system has five receptor subtypes (MC1R through MC5R), each with its own tissue distribution and proposed functions. Research separates the two Melanotans mainly by how selectively they engage these receptors.
Melanotan I (also called MT-1 or afamelanotide) is described in the literature as a relatively selective MC1R agonist. MC1R sits mostly in melanocytes, the skin cells that produce the pigment melanin. Studies report that MT-1's activity concentrates at this receptor, which is why it has been investigated in dermatology research, including work on photoprotection and pigmentation.
Melanotan II (MT-2) is characterized in research as a non-selective melanocortin agonist. It binds with meaningful affinity at MC1R, MC3R, MC4R, and MC5R. MC4R is expressed in the central nervous system and is associated in the research literature with a wider range of physiological signals. That broader receptor profile shows up in the wider scope of effects described in MT-2 research relative to MT-1.
Research Profiles at a Glance
| Feature | Melanotan I (MT-1 / Afamelanotide) | Melanotan II (MT-2) |
|---|---|---|
| Primary receptor target | MC1R (selective) | MC1R, MC3R, MC4R, MC5R (non-selective) |
| Structural type | Linear 13–amino-acid α-MSH analogue | Cyclic (lactam-bridged) heptapeptide |
| Main research areas | Skin pigmentation, photoprotection | Pigmentation, CNS-linked pathways |
| Regulatory note | Approved (EMA 2014; FDA 2019) for erythropoietic protoporphyria | Not approved in any jurisdiction; research use only |
| Common research form | Subcutaneous implant or injectable (research settings) | Injectable (research settings) |
Afamelanotide (MT-1) has a regulatory history of its own. The European Medicines Agency approved it under the brand name Scenesse for erythropoietic protoporphyria (EPP) in 2014, and the U.S. Food and Drug Administration approved the Scenesse implant for the same indication in October 2019. That makes it one of the few melanocortin peptides to reach approved therapeutic status anywhere, which sets it apart from MT-2, still outside approved medical use worldwide. Per its manufacturer, in 2025 the EMA amended the Scenesse label to allow more frequent dosing in EPP (roughly every two months, year-round), a sign of continued regulatory engagement with the approved product.
What Research Reports
Studies on Melanotan I focus mostly on its ability to stimulate melanogenesis, the production of melanin, through MC1R activation in the skin. Research in EPP patients, for instance, looks at whether increased melanin can reduce photosensitivity. Because its receptor binding is more targeted, researchers note a narrower effect profile than MT-2.
Melanotan II research covers more ground, in line with its multi-receptor activity. The literature describes pigmentation responses similar to MT-1, alongside CNS-mediated signals attributed to MC4R engagement. Researchers have pointed to MT-2's cyclic structure, a structural difference from MT-1's linear form, as a contributor to its higher potency and broader binding profile. The cyclic modification is also commonly cited as conferring greater metabolic stability.
Both compounds are described in research as superpotent relative to native α-MSH. The [Nle4, D-Phe7] modifications shared by both are reported to be on the order of a thousand-fold more potent than the native hormone, so they need lower concentrations to activate their target receptors. Neither should be read through the lens of approved therapies when discussed in a research context.
MT-2 has drawn repeated regulatory and public-health warnings. The FDA has issued warning letters against firms marketing injectable Melanotan II as an unapproved tanning product, and agencies in the UK and several other countries have cautioned against its use. These actions are a reminder that MT-2 is not an approved drug and is not intended for human consumption.
Key Distinctions for Research Context
For researchers weighing these compounds, the main split is selectivity versus breadth. MT-1/afamelanotide hits a narrower receptor target (MC1R), which researchers working on pigmentation or photoprotection pathways often prefer for mechanistic specificity. MT-2's multi-receptor engagement makes it a broader research tool, but it adds variables to experimental design.
Both compounds are supplied by research chemical vendors and peptide manufacturers. Independent laboratory testing services, such as those aggregated on this site, can provide third-party purity and concentration data for specific batches. As with all research peptides, purity verification and documented sourcing are standard practice in legitimate research settings.
Sources
- Afamelanotide — Wikipedia (structure, sequence, regulatory history)
- Melanotan II — Wikipedia (cyclic heptapeptide, receptor profile)
- European Medicines Agency — Scenesse (afamelanotide)
- FDA — Drug Trials Snapshots: SCENESSE (afamelanotide), approved October 2019
- DermNet NZ — Melanotan II (safety and regulatory warnings)
- Finnrick — peptide vendor and product listings
- PeptideBenchmark — independent batch testing data