OnePin Peptide Library · Skin
MT-I (Melanotan I)
MT-1 · MT1 · Melanotan I · Afamelanotide · Scenesse
MT-I (Melanotan I, INN: afamelanotide, brand: Scenesse) is a synthetic linear analog of α-melanocyte-stimulating hormone (α-MSH) - a 13-amino-acid linear peptide with substitutions ([Nle4, D-Phe7]-α-MSH) that confer high MC1R receptor selectivity and increased metabolic stability. FDA-approved (October 2019) and EMA-approved as Scenesse for the prevention of phototoxicity in adult patients with erythropoietic protoporphyria (EPP) - a rare genetic disease causing severe sunlight-induced skin pain.
FDA Scenesse: 16 mg implant placed by clinician every 2 months. Off-label injection: 0.5-1 mg daily SubQ for 1-2 weeks during 'tan loading,' then 1-2x weekly maintenance. Reconstitute lyophilized peptide with bacteriostatic water; refrigerate. Light-sensitive after reconstitution.
Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.
How it works
MT-I binds the melanocortin-1 receptor (MC1R) on melanocytes in skin and hair follicles, activating the cAMP/PKA cascade. PKA phosphorylates the microphthalmia-associated transcription factor (MITF), which upregulates expression of melanogenesis enzymes (tyrosinase, TRP-1, TRP-2). Net effect: increased eumelanin (the photoprotective black/brown melanin) production and pigment transfer to keratinocytes.
MC1R Selectivity
MT-I has 10-100x higher affinity for MC1R than for the other melanocortin receptors (MC3R, MC4R, MC5R). This selectivity contrasts with MT-II's broader profile and explains MT-I's restricted side-effect profile (no significant appetite, libido, or erection effects).
Eumelanin Shift
Activation of MC1R favors eumelanin synthesis over pheomelanin - eumelanin is the photoprotective pigment that absorbs UV radiation. The mechanism is therapeutically meaningful for EPP patients, who lack effective photoprotection due to porphyrin accumulation.
Linear Peptide Stability
Linear 13-amino-acid analog with [Nle4, D-Phe7] substitutions (replacing native Met4 with norleucine and Phe7 with D-phenylalanine). These substitutions resist enzymatic degradation and extend the molecule's bioavailability vs native α-MSH.
Clinical Delivery
FDA-approved as Scenesse implant - 16 mg sustained-release implant placed subcutaneously every 2 months. Provides sustained α-MSH receptor activation over weeks. Off-label use is via daily SubQ injection of reconstituted lyophilized peptide.
No Met or Cys
Linear peptide without methionine or cysteine residues - chemistry-compatible with copper-conjugated peptides like GHK-Cu. No disulfide bonds means no copper-driven oxidation concerns.
What to expect
Week 1-2: existing pigmented spots darken; early tan develops with UV exposure.
Week 2-4: deeper, more even tan develops with continued UV exposure.
Week 4+: tan stabilizes; maintenance dosing 1-2x weekly sustains. Without UV exposure, MT-I produces little visible effect.
Evidence
Interactions & stacking
What's safe to combine, and what belongs in a separate pin.
Keep separate
Side effects & safety
Commonly reported
- Mild injection site reaction
- Mild nausea (less than MT-II)
- Mild headache (early doses)
- Darkening of existing moles and freckles (expected pharmacologic effect)
- Increased number of visible nevi (some users report new dark spots)
Less common & notes
- Persistent skin pigmentation in unexpected sites (lips, nipples, genitals) - typically reversible.
- Theoretical risk of dysplastic nevi activation or melanoma promotion - relative contraindication in patients with melanoma history or significant atypical nevi.
- Severe injection site reactions are rare.
- Long-term safety in off-label use beyond Scenesse trial / surveillance data is incompletely characterized.
- EPP-population safety established through Scenesse Phase 3 trials and post-marketing surveillance.
Pharmacokinetics
Storage. Lyophilized vial: refrigerate (2-8°C / 36-46°F) or freeze (-20°C) for long-term storage. After reconstitution with bacteriostatic water: refrigerate, use within 21-28 days. LIGHT-SENSITIVE - protect from light especially after reconstitution. Discard if cloudy, discolored, or contains particulates. Scenesse implant: clinician-stored per manufacturer specifications.
Regulatory status
FDA-approved as Scenesse (afamelanotide, 16 mg implant) since October 2019 for adult patients with erythropoietic protoporphyria (EPP). EMA-approved 2014 for same indication. Outside EPP, off-label tanning use is unapproved. Sale of MT-I as a research peptide for off-label tanning use is technically prohibited by FDA but enforcement is variable. Some sport organizations prohibit melanocortin agonists under performance-enhancement rules. Pregnancy category data inadequate.
Put it to work
Calculate, log & track
Open MT-I (Melanotan I) straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.
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The guide & community
The complete MT-I (Melanotan I) walkthrough, real protocol discussion and coaching live inside the BlessUp community on Skool.
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