Research Applications
Sunless Tanning and UV Protection Research
MT-II's ability to stimulate melanin production without UV exposure was its original research application. Studies demonstrate significant skin darkening across all skin types, potentially reducing UV-induced DNA damage by providing a baseline melanin "shield." However, concerns about uncontrolled melanocyte stimulation have limited clinical development.
Sexual Dysfunction
Clinical trials demonstrated efficacy for both male erectile dysfunction and female sexual arousal disorder. MT-II was the proof-of-concept compound that led to PT-141 development. Effects include enhanced libido, improved erections, and increased genital arousal in both sexes.
Obesity and Appetite Research
MC4R-mediated appetite suppression makes MT-II a research tool for studying melanocortin appetite regulation. Significant reductions in food intake and body weight have been demonstrated in clinical studies.
Melanoma Prevention Research
The concept of pharmacological tanning (melanin production without UV) as skin cancer prevention is an active research area. Whether MT-II-induced melanogenesis provides genuine photoprotection without increasing melanoma risk remains under investigation.
Mechanism of Action
MC1R Activation (Tanning)
MT-II activates MC1R on melanocytes in the basal layer of the epidermis. MC1R signaling through cAMP/PKA/CREB increases transcription of MITF (microphthalmia-associated transcription factor), which drives expression of melanin synthesis enzymes — tyrosinase, TRP-1, and TRP-2. This produces eumelanin (brown/black pigment) deposition, resulting in skin darkening without UV exposure (though UV exposure accelerates the process).
MC3R/MC4R Activation (Sexual Function)
Like PT-141, MT-II activates hypothalamic MC3R and MC4R, stimulating sexual desire and arousal through dopaminergic and oxytocinergic pathways. The sexual effects are generally more pronounced than with PT-141 due to MT-II's broader receptor activation profile.
MC4R Activation (Appetite Suppression)
MC4R activation in the hypothalamic arcuate nucleus stimulates POMC/α-MSH signaling and suppresses NPY/AgRP neurons, producing significant appetite reduction. This anorexigenic effect can cause notable food intake reduction during MT-II use.
MC4R-Mediated Lipolysis
Hypothalamic MC4R activation enhances sympathetic nervous system outflow to adipose tissue, promoting lipolysis through β3-adrenergic receptor stimulation. This contributes to fat loss effects observed with MT-II use.
Biological Pathways
cAMP/PKA/MITF Melanogenesis
MC1R→Gαs→adenylyl cyclase→cAMP→PKA→CREB→MITF→tyrosinase/TRP-1/TRP-2: The melanogenic cascade. MITF is the master transcription factor for melanocyte differentiation and melanin production.
MC4R/POMC/α-MSH Anorexigenic Pathway
MC4R activation enhances endogenous melanocortin signaling, creating a positive feedback loop. POMC neuron activation suppresses food intake through α-MSH release acting on downstream MC4R in the paraventricular nucleus.
Dopamine/Oxytocin Sexual Arousal
MC4R→dopamine release (VTA/NAc)→D1/D2 activation + MC4R→PVN oxytocin→pelvic autonomic neurons: Dual pathway enhancing both psychological desire (dopamine) and physiological arousal (oxytocin/genital blood flow).
p53/DNA Damage Melanocyte Response
An important safety pathway: MC1R activation can enhance DNA repair in melanocytes through p53-mediated nucleotide excision repair (NER). However, sustained melanocyte proliferation without UV exposure may also mask UV damage, potentially increasing melanoma risk in certain contexts.
Dosage Information
Calculation Results
Syringe Fill Level (100u syringe)
Protocols
No protocols featuring this peptide yet.
Browse All ProtocolsStability & Storage
Melanotan II is supplied as a white lyophilized powder. Store at -20°C for long-term stability (18-24 months) or 2-8°C for up to 6 months. The cyclic structure provides enhanced protease resistance compared to linear melanocortin analogs.
Reconstitute with bacteriostatic water. Store reconstituted solution at 2-8°C and use within 21-28 days. MT-II is photosensitive — protect from prolonged light exposure which can cause tryptophan oxidation. The solution should remain clear and colorless; any discoloration indicates degradation.
Side Effects & Precautions
Nausea (Very Common)
Nausea is the most common acute side effect (50-70% of users), occurring 30-60 minutes post-injection. Generally dose-dependent and often reduces with repeated use. Starting with low doses and gradual titration helps minimize nausea.
Facial Flushing
Pronounced facial flushing and warmth occur in most users, lasting 30-60 minutes post-injection. Related to melanocortin-mediated vasodilation.
Spontaneous Erections
Unwanted erections are commonly reported in males, sometimes lasting 2-4 hours. Related to MC3R/MC4R-mediated sexual arousal pathways. In rare cases, priapism (prolonged painful erection) has been reported and requires medical attention.
Mole Changes and Darkening
MT-II stimulates ALL melanocytes, including those in moles (nevi). Existing moles may darken, enlarge, or change appearance — potentially masking melanoma development. Dermatological monitoring is strongly recommended. New moles may also appear.
Appetite Suppression
Significant reduction in appetite and food intake occurs through MC4R-mediated anorexia. This is dose-dependent and persistent during use.
Fatigue and Drowsiness
Lethargy and sleepiness are reported by many users, likely related to central melanocortin effects on arousal circuits.
Skin Hyperpigmentation (Uneven)
Tanning can be patchy or uneven, with some areas (face, arms) darkening more than others. Freckles may darken dramatically. Genital darkening is common.
Potential Melanoma Risk
The most serious safety concern. By stimulating melanocyte proliferation without UV-mediated DNA damage checkpoints, MT-II may promote melanoma development, particularly in individuals with pre-existing dysplastic nevi or melanoma risk factors. Several case reports have linked MT-II use to melanoma, though causation is not definitively established.
Research Use Only. This information is for educational and research purposes only. Not intended for medical advice or self-medication.
Regulatory Status
Melanotan II is not approved by the FDA, EMA, TGA, or any major regulatory authority for any indication. Multiple regulatory agencies have issued public health warnings against its use, including the FDA, EMA, TGA (Australia), and MHRA (UK).
MT-II is classified as an unapproved and unregulated substance. It is widely available from research chemical suppliers and online peptide vendors but is sold without manufacturing quality controls, dosing standardization, or safety oversight.
MT-II is not explicitly on the WADA prohibited list, though it may be captured under the S0 (Non-Approved Substances) category. Its regulatory status varies by jurisdiction but it is generally illegal to sell for human consumption.
Research Studies
Melanotan II: A Synthetic Analogue of α-MSH
Hadley ME, Haskell-Luevano C, et al.
Melanotan II Clinical Trials for Tanning
Dorr RT, Lines R, Levine N, et al.
Melanocortin Peptides and Male Sexual Function
Wessells H, Fuciarelli K, Hansen J, et al.
Health Risks Associated with Melanotan Products
Brennan R, Wells JG, Van Hout MC.
α-MSH and Melanocortin Receptors in Melanogenesis
Garcia-Borron JC, Sanchez-Laorden BL, Jimenez-Cervantes C.
