Overview
Melanotan-1, marketed as afamelanotide (trade name Scenesse), is a synthetic 13-amino-acid analog of α-melanocyte-stimulating hormone (α-MSH) with the sequence [Nle⁴, D-Phe⁷]-α-MSH. It was developed at the University of Arizona in the 1980s and is the first and only melanocortin-1 receptor (MC1R) agonist approved by the FDA, receiving authorization in 2019 for the prevention of phototoxicity in adults with erythropoietic protoporphyria (EPP).
Afamelanotide binds with high affinity to MC1R on epidermal melanocytes and shifts pigment production from photoprotectively weak pheomelanin toward darker, UV-absorbing eumelanin. The result is a generalized increase in skin pigmentation that is independent of UV exposure and confers substantial protection against UV-A and visible light—wavelengths that trigger painful phototoxic reactions in EPP.
EPP is a rare inherited porphyria in which protoporphyrin IX accumulates in skin, where light exposure generates reactive oxygen species and excruciating burning pain. Before afamelanotide, EPP patients had no effective treatment; they could spend only minutes in sunlight without provoking a reaction. Pivotal Phase III trials (CUV029, CUV039) showed that scheduled afamelanotide implants approximately doubled pain-free outdoor time and dramatically improved quality of life.
Beyond EPP, afamelanotide is being studied for vitiligo (in combination with narrowband UVB), Hailey-Hailey disease, and other photosensitivity disorders. It should not be confused with Melanotan-2 (MT-2), a non-selective melanocortin agonist sold illicitly for cosmetic tanning with a much broader and less well-characterized safety profile.
Quick facts
- Mechanism
- α-MSH analog and MC1R agonist driving eumelanogenesis for UV photoprotection
- Primary use
- Phototoxicity prevention in EPP; photoprotection research
- Evidence
- strong
- FDA
- Approved
- Route
- Subcutaneous bioresorbable implant (16 mg) every 60 days
- Typical results
- Visible skin pigmentation within 2 days of implant; pain-free sun exposure roughly doubles in EPP patients
Chemical information
MT-1 (C₇₈H₁₁₁N₂₁O₁₉) is a hormonal compound with a molecular weight of 1646.8 g/mol. Its structural characteristics underpin its biological activity in hormonal signaling and endocrine function.
How MT-1 works
Afamelanotide is a structurally modified α-MSH in which methionine at position 4 is replaced with norleucine and L-phenylalanine at position 7 is replaced with D-phenylalanine. These substitutions confer resistance to proteolytic degradation and dramatically increase potency at MC1R on epidermal melanocytes. Receptor activation triggers Gs-coupled adenylyl cyclase activity, elevates intracellular cAMP, and induces microphthalmia-associated transcription factor (MITF), which drives expression of tyrosinase and other enzymes that shift pigment synthesis toward eumelanin.
Eumelanin is a far more effective absorber of UV and visible-light photons than pheomelanin and functions as a chemical antioxidant that neutralizes reactive oxygen species generated by porphyrin photoactivation. By increasing the eumelanin/pheomelanin ratio across the entire integument, afamelanotide produces a uniform, sun-independent photoprotective shield that begins within 2–3 days of implant placement and persists for roughly 60 days.
Afamelanotide also has direct anti-inflammatory and antioxidant effects independent of pigmentation. MC1R activation on keratinocytes and immune cells suppresses NF-κB signaling, reduces pro-inflammatory cytokine release, and upregulates endogenous antioxidant defenses. These effects likely contribute to the symptom relief observed in EPP patients before maximal pigmentation is achieved.
The drug is delivered as a 16 mg controlled-release bioresorbable implant inserted subcutaneously above the iliac crest. Plasma levels peak around day 2–3, then decline over 4–6 weeks while pigmentation persists for the full dosing interval. Implants are administered every 60 days during periods of high light exposure, typically 3–4 times per year.
- MC1R agonism: Potent, long-acting α-MSH analog selective for the melanocortin-1 receptor
- Eumelanogenesis shift: Increases dark, photoprotective eumelanin at the expense of pheomelanin
- UV-independent pigmentation: Generates protective tanning without sun exposure
- Anti-inflammatory: Suppresses NF-κB and reactive-oxygen-driven skin damage
- Controlled-release implant: 60-day bioresorbable depot provides steady photoprotection
Pharmacokinetics
| Parameter | Value | Significance |
|---|---|---|
| Molecular Mass | 1646.8 g/mol | Mid-size peptide suited to subcutaneous depot delivery |
| Tmax | ~48–72 hours after implant | Slow release from bioresorbable matrix |
| Elimination half-life | ~30 minutes (free drug) | Plasma clearance is rapid; depot drives sustained exposure |
| Duration of effect | ~60 days per 16 mg implant | Defines standard dosing interval |
| Bioavailability | Effectively 100% from implant | Bypasses GI degradation and hepatic first-pass |
Dosing & administration
MT-1 dosing varies by indication and individual factors. Refer to the official prescribing information for approved indications.
Any use should be conducted under qualified medical supervision with appropriate monitoring of safety markers.
Side effects & safety
Safety data for MT-1 is established for approved indications via clinical trials. Long-term effects in humans remain incompletely characterized.
Common
- • Generalized skin darkening (intended pharmacologic effect)
- • Nausea and decreased appetite in the days following implant
- • Headache and fatigue
- • Implant-site erythema, bruising, or hyperpigmentation
- • Mild dizziness and flushing
Serious / potential risks
- • Persistent new or changing pigmented skin lesions (requires dermatologic evaluation)
- • Severe hypersensitivity reactions (rare)
- • Risk of masking melanoma — full-body skin exams every 6–12 months are recommended
- • Theoretical cardiovascular effects from broader melanocortin activity
Drug interactions
| Medication | Interaction | Recommendation |
|---|---|---|
| Photosensitizing drugs (tetracyclines, fluoroquinolones) | Pigmentation may modify perceived phototoxicity | Monitor skin response; afamelanotide does not replace photoprotective behavior |
| Other melanocortin agonists (MT-2, bremelanotide) | Additive MC receptor activation | Avoid combination; risk of excessive pigmentation and cardiovascular effects |
| Topical depigmenting agents (hydroquinone) | Opposing effects on melanogenesis | Discuss with prescriber if cosmetic depigmentation is desired |
| Immunosuppressants | No clinically significant interaction known | Standard monitoring; afamelanotide has been used safely in transplant recipients |
Storage & handling
Lyophilized (powder)
- • Store at -20°C to 4°C (freezer or refrigerator)
- • Protect from light and moisture
- • Stable for 12–24 months when stored properly
- • Keep in original sealed container until reconstitution
Reconstituted solution
- • Refrigerate at 2–8°C after reconstitution
- • Use bacteriostatic water for multi-dose reconstitution
- • Typical stability: 14–28 days refrigerated
- • Do not freeze reconstituted solution
Cost & availability
| Source | Cost | Notes |
|---|---|---|
| Research suppliers | Varies widely | Quality and purity vary significantly between sources |
| Compounding pharmacies | Prescription required | Higher quality assurance and purity testing |
The bottom line
MT-1 is a hormonal compound with research interest in melanocortin, skin protection, epp. While preclinical evidence is encouraging, it has received FDA approval for specific indications. Any use should be under qualified medical supervision.
Best for
- • Researchers studying hormonal signaling and endocrine function
- • Individuals interested in melanocortin under medical guidance
Not for
- • Self-administration without medical supervision
- • Pregnant or breastfeeding individuals
- • Individuals with contraindicated conditions
Related compounds
Frequently asked questions
References
- [1] Langendonk JG, Balwani M, Anderson KE, et al.. Afamelanotide for erythropoietic protoporphyria. N Engl J Med (2015). doi: 10.1056/NEJMoa1411481 PMID: 26154953
- [2] Minder EI, Barman-Aksoezen J, Schneider-Yin X.. Pharmacokinetics and pharmacodynamics of afamelanotide and its clinical use in dermatologic disorders. Clin Pharmacokinet (2017). doi: 10.1007/s40262-016-0501-5 PMID: 28063031
- [3] Lim HW, Grimes PE, Agbai O, et al.. Afamelanotide and narrowband UV-B phototherapy for the treatment of vitiligo: a randomized multicenter trial. JAMA Dermatol (2015). doi: 10.1001/jamadermatol.2014.3859 PMID: 25471534
- [4] U.S. Food and Drug Administration. Scenesse (afamelanotide) prescribing information. FDA Label (2019).