Receptor mechanism, dosage tables by application, reconstitution guide, clinical data summary, side effect profile, and COA-verified vendor pricing — all in one place.
Melanotan II is a synthetic cyclic heptapeptide analog of α-MSH with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂. Its cyclic structure and D-phenylalanine substitution confer greater metabolic stability and receptor potency compared to linear α-MSH. It activates MC1R, MC3R, and MC4R — producing pigmentation, sexual function, and appetite modulation effects through different receptor populations.
| Property | Value |
|---|---|
| Classification | Synthetic cyclic melanocortin receptor agonist |
| Sequence | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ |
| Molecular weight | ~1,024 Da |
| Receptors | MC1R, MC3R, MC4R (non-selective agonist) |
| Half-life | ~1 hour (SubQ); ~30 min (IV) |
| Routes | Subcutaneous injection, intranasal |
| Storage | Lyophilized: refrigerate; reconstituted: refrigerate, use within 30 days, protect from light |
| Reconstitution | Bacteriostatic water |
| Regulatory status | Not approved in any jurisdiction for human use; research compound |
| Clinical development | Phase 1/2 trials conducted 1990s–2000s; not advanced to approval |
MT-II dosing in clinical trials and research community protocols varies significantly by application. Lower doses are used for pigmentation research; higher doses for sexual function applications. Nausea is the primary dose-limiting factor.
| Application | Dose Range | Frequency | Notes |
|---|---|---|---|
| Pigmentation (loading) | 500mcg – 1mg SubQ | Daily for 1–2 weeks | Initial tanning phase; titrate up from low dose |
| Pigmentation (maintenance) | 500mcg SubQ | 2–3x per week | After initial loading to maintain pigmentation |
| Sexual function | 500mcg – 1mg SubQ | As needed, 1–2 hrs prior | Onset ~1 hour; erection research in men |
| Clinical trial (Vickers 2003) | 0.025 mg/kg SubQ | Single dose | ~1.75mg for 70kg subject |
| Intranasal | 2–4mg | As needed | Lower bioavailability than SubQ; less predictable |
Nausea is the most common adverse effect of MT-II and is dose-dependent. Research protocols universally recommend starting at 250–500mcg and titrating upward. Taking MT-II before sleep reduces nausea impact. Some researchers pre-dose with anti-nausea agents in higher-dose protocols.
MT-II commonly comes in 10mg vials. Reconstitute with 2mL bacteriostatic water for a 5mg/mL (5,000 mcg/mL) concentration. At a 500mcg research dose, that's 0.1mL (10 units on a U100 syringe).
| Vial | BAC Water | Concentration | Volume per 500mcg | Volume per 1mg |
|---|---|---|---|---|
| 10mg | 2mL | 5,000 mcg/mL | 0.10mL (10 units) | 0.20mL (20 units) |
| 10mg | 1mL | 10,000 mcg/mL | 0.05mL (5 units) | 0.10mL (10 units) |
Early University of Arizona clinical studies in fair-skinned volunteers demonstrated that MT-II produced dose-dependent skin darkening over 2–3 weeks of daily SubQ dosing. The pigmentation was consistent with eumelanin production, providing measurable photoprotection in treated skin areas. Pigmentation fades gradually after cessation — typically over several months.
Dorr et al. (1996) and subsequent trials demonstrated that MT-II produced penile erection in a significant proportion of men with erectile dysfunction, including in subjects who were non-responsive to other treatments. The central mechanism (hypothalamic MC4R) rather than vascular mechanism differentiates this from PDE5 inhibitors. This research directly led to PT-141 development and eventual FDA approval — the strongest indirect validation of MT-II's mechanism.
Multiple preclinical studies show MT-II reduces food intake and body weight in rodent models via MC4R in the hypothalamus. Human trial data is more limited for this application specifically. The weight loss observed in clinical subjects during tanning research was a secondary observation — not the primary endpoint of those studies.
MC4R's role in dopaminergic reward circuits has led to research in substance use models. MT-II has shown effects on alcohol preference and compulsive eating behavior in preclinical studies, an emerging research area connecting melanocortin signaling to addiction biology.
MT-II has a more complex side effect profile than more selective melanocortin peptides, reflecting its non-selective receptor activation.
The darkening of existing moles with MT-II use is well-documented in research literature. While there is no confirmed evidence that MT-II causes malignant transformation, the theoretical concern about melanocyte stimulation in dysplastic nevi warrants dermatological monitoring. This is among the reasons MT-II did not advance to FDA approval while PT-141 did.
COA-verified vendor pricing with promo codes. Tegridy Research currently carries Melanotan II.
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