MT-2 (Melanotan II)

What It Is

Melanotan II (MT-2) is a synthetic analog of alpha-melanocyte-stimulating hormone (α-MSH) that binds to melanocortin receptors (MC1R, MC3R, MC4R, and MC5R) with broad activity. It was originally developed at the University of Arizona for skin tanning via MC1R-mediated melanogenesis, but its non-selective melanocortin receptor binding produces multiple effects including appetite suppression (MC4R), sexual arousal (MC4R/MC3R), and modulation of inflammatory pathways. MT-2 has been extensively studied in preclinical and small clinical settings for erectile dysfunction and female sexual arousal disorder, though its non-selective receptor profile produces unpredictable side effects including nausea, facial flushing, and involuntary erections. The more selective MC4R agonist bremelanotide (PT-141/Vyleesi) was developed from MT-2 to isolate the sexual function effects and gained FDA approval in 2019 for hypoactive sexual desire disorder in women. Melanotan II has been associated with melanoma-related safety concerns — case reports have documented atypical nevi (mole changes) and rare melanoma diagnoses in users, though causality has not been established in controlled studies. As of May 2026, MT-2 is expected to remain on the FDA's Category 2 restricted list, likely staying prohibited from compounding due to its safety profile concerns. It is classified as a prohibited substance by WADA and is not FDA-approved for any indication.

Regulatory Status

Why Researchers Study It

Melanotan II is studied for its unique ability to activate multiple melanocortin receptor subtypes simultaneously. Its broad-spectrum activity has provided key insights into melanocortin receptor pharmacology and led directly to the development of the FDA-approved drug bremelanotide (PT-141). Current research interest centers on understanding MC4R-mediated appetite suppression and the relationship between melanogenesis stimulation and melanoma risk.

Proposed Mechanisms

• Binds MC1R on melanocytes, stimulating melanin production (tanning effect)
• Activates MC4R in the hypothalamus, producing appetite suppression and sexual arousal
• Non-selective binding to MC3R and MC5R contributes to metabolic and anti-inflammatory effects
• Increases intracellular cAMP in melanocytes via MC1R activation
• May modulate inflammatory cytokine production through central melanocortin signaling

Evidence Snapshot

Commonly Discussed Benefits

Safety & Cautions

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Citations

1. [1] Dorr RT. et al. — Effects of a superpotent melanotropic peptide. Life Sci. 1996 PubMed

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