Source comparison
Melanotan-1 vs Melanotan-2: Structure, Selectivity, and Safety Comparison
The table below contrasts the two most-researched melanocortin peptide analogs. Despite similar names, their receptor profiles and clinical applications diverge significantly. Amino Acid Structure 13-residue linear analog of α-MSH 7-residue cyclic lactam analo
This comparison does not assign a generated winner or score.
- The table below contrasts the two most-researched melanocortin peptide analogs. Despite similar names, their receptor profiles and clinical applications diverge significantly.
- Amino Acid Structure
- 13-residue linear analog of α-MSH
- 7-residue cyclic lactam analog
- MT1's longer sequence increases MC1R selectivity; MT2's cyclic structure enhances pan-melanocortin binding
- Primary Receptor Target
- MC1R (melanocortin-1 receptor)
- MC1R, MC3R, MC4R, MC5R (pan-agonist)
- MT1 avoids off-target CNS and appetite effects by sparing MC3R/MC4R activation
- Half-Life (Subcutaneous)
- 90–120 minutes
- 2–4 hours
- MT2's longer half-life allows less frequent dosing but increases systemic exposure duration
- Approved Indications
- EPP (EU, Australia, Switzerland)
- None (research-only globally)
- MT1 has undergone Phase III trials and regulatory review; MT2 remains unapproved
- Common Adverse Events
- Nausea (18%), injection site darkening (12%), fatigue (9%)
- Nausea (45%), spontaneous erections (male, 60%), flushing (38%), hypertension transient (15%)
- MT2's MC4R agonism drives appetite/sexual effects; MT1's selectivity reduces incidence
- Melanogenic Potency
- Moderate (requires 10–14 days visible effect)
- High (visible pigmentation 3–7 days)
- MT2's pan-receptor activity accelerates melanin synthesis but at cost of side effect burden
- Bottom Line
- MC1R-selective, clinically validated for photoprotection, regulatory-approved formulation exists
- Potent but non-selective, higher side effect risk, no approved formulations, research contexts only
- Choose MT1 for photoprotection research; MT2 for receptor promiscuity studies or models requiring rapid melanogenesis
- The selectivity difference explains why melanotan-1 advanced through regulatory approval while melanotan-2 did not. MC3R and MC4R activation. The pathway MT2 strongly stimulates. Drives central appetite suppression, increased sympathetic tone, and sexual side effects via hypothalamic circuits. Those effects are reproducible and dose-dependent, documented in every Phase I safety trial MT2 entered. Melanotan-1 avoids those receptors almost entirely, binding MC1R with 200–300× greater affinity than MC4R.
- Another structural note: melanotan-2's lactam bridge (the cyclic bond between positions 4 and 10) increases resistance to enzymatic degradation, extending half-life but also increasing the duration that off-target receptors remain activated. Melanotan-1's linear structure is metabolized faster, reducing systemic exposure time. For research protocols where minimizing off-target effects is critical, MT1 is the appropriate choice.