Source comparison
Melanotan-1/MT-1: Comparison Overview
Molecular Structure Linear 13-amino-acid peptide (Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2) Cyclic 7-amino-acid peptide with disulfide bridge (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2) MT-1 is longer and lacks the ring structure that inc
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- Molecular Structure
- Linear 13-amino-acid peptide (Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2)
- Cyclic 7-amino-acid peptide with disulfide bridge (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2)
- MT-1 is longer and lacks the ring structure that increases MT-2 potency
- MT-1 is structurally closer to endogenous α-MSH, making receptor interaction more predictable
- Receptor Selectivity
- High MC1R selectivity (1,000-fold over MC3R/MC4R); minimal MC4R binding
- Broad melanocortin receptor binding (MC1R, MC3R, MC4R, MC5R)
- MC4R activation drives appetite suppression and sexual effects in MT-2
- MT-1 produces pigmentation without central nervous system side effects
- Clinical Approval
- FDA and EMA approved as Scenesse (afamelanotide) for erythropoietic protoporphyria
- No regulatory approval for any indication; used exclusively in research contexts
- Scenesse uses a 16 mg subcutaneous implant formulation
- MT-1 is the only synthetic melanocortin with formal drug approval
- Typical Dosing
- 0.5–1.0 mg/day subcutaneous injection (research protocols); 16 mg implant over 60 days (Scenesse)
- 0.25–1.0 mg per injection due to higher per-milligram potency
- MT-2 dosing is lower because receptor affinity is approximately 10× higher than MT-1
- MT-1 requires higher absolute doses but produces more targeted effects
- Reported Side Effects
- Injection-site reactions, mild nausea (<5% in clinical trials), temporary flushing
- Nausea (30%+ in anecdotal reports), spontaneous erections, appetite suppression, facial flushing
- MT-2's side effects stem from MC3R/MC4R activation in the hypothalamus and brainstem
- MT-1's side effect profile is significantly milder and more tolerable across protocols
- Half-Life
- Approximately 30–60 minutes (IV); extended-release implants modify this
- Approximately 30–60 minutes (subcutaneous injection)
- Short half-life requires daily dosing for both peptides unless formulated as sustained-release
- Neither peptide accumulates. Steady-state pigmentation reflects cumulative receptor activation over weeks