Melanotan 2

Cyclic superpotent alpha-MSH analog researched for melanogenesis and sexual function; never approved and widely used off-label.

Overview

Melanotan 2 is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone developed in the 1980s by the group of Victor Hruby and Mac Hadley at the University of Arizona. It is a potent, long-acting agonist at melanocortin receptors, especially MC1R, and was designed to induce melanogenesis. Despite decades of research interest in tanning and, through its relative bremelanotide, in sexual function, melanotan 2 itself was never approved as a drug and is sold only on unregulated research markets.

Mechanism

The cyclic structure confers resistance to enzymatic degradation and high receptor potency. MC1R activation drives melanin synthesis, while activity at central melanocortin receptors (MC3R and MC4R) is thought to underlie effects on appetite and sexual arousal reported in animal and human research.

Dosing

In published research protocols melanotan 2 is administered by subcutaneous injection, with dosing regimens reported in individual studies; a related analog, bremelanotide, is an approved drug with its own labeling for hypoactive sexual desire disorder. Off-label use of melanotan 2 from unregulated sources has no valid dosing basis.

Expected Effects

skin darkening through eumelanin induction in research and off-label use
reported increases in sexual arousal in some human studies of related analogs
appetite suppression in animal studies via melanocortin-4 receptor activity

Side Effects & Tolerability

Documented effects include nausea, flushing, fatigue, decreased appetite, spontaneous penile erections, and darkening or enlargement of existing moles and freckles. Case reports in the medical literature describe more serious adverse events associated with unregulated use, including rhabdomyolysis and melanocytic lesion changes, underscoring the risks of non-pharmaceutical material.

Storage

Lyophilized melanotan 2 should be stored desiccated, protected from light, and kept frozen at -20 deg C or below; reconstituted solutions should be refrigerated at 2-8 deg C and used promptly.