Melanotan II Dosage Calculator

Melanotan II (MT-II) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH), developed at the University of Arizona in the 1980s and 1990s as part of a broader program to create tanning agents for photoprotection and as treatments for sexual dysfunction. The peptide has the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ and is a non-selective melanocortin receptor agonist with activity at MC1R, MC3R, MC4R, and MC5R subtypes.

Melanotan II rose to prominence in the 1990s following human studies at the University of Arizona that demonstrated potent pigmentation induction after low-dose subcutaneous administration, as well as spontaneous penile erections in male subjects — an unexpected side effect that led to a separate research track focused on sexual dysfunction. The compound's MC4R agonism is responsible for both the erectile activity and appetite suppression effects, while MC1R agonism drives melanogenesis (skin darkening). Despite the demonstrated biological activity, Melanotan II has not been approved by any regulatory agency and remains a research compound.

Melanotan II activates multiple melanocortin receptor subtypes simultaneously, distinguishing it from more selective compounds. MC1R agonism in melanocytes stimulates the production and release of eumelanin (the brown/black form of melanin), producing dose-dependent skin and hair darkening. This pathway is the basis for the original tanning research interest in the compound.

MC4R agonism in the central nervous system drives the compound's effects on sexual arousal and penile/clitoral erection in animal models and human studies. The PT-141 derivative (bremelanotide), a truncated and structurally modified analog of Melanotan II, has been selectively developed and approved (Vyleesi) for hypoactive sexual desire disorder in premenopausal women, based on this MC4R mechanism. MC4R activation also drives reduced food intake and increased energy expenditure, explaining the appetite suppression commonly reported in Melanotan II research. MC3R agonism contributes to cardiovascular and metabolic regulatory effects that have been studied in rodent models.

Melanotan II lyophilized powder is reconstituted with bacteriostatic water for injection. For a 10 mg vial, inject 5 mL of bacteriostatic water slowly against the inner glass wall. Allow to rest for 60 seconds, then swirl gently until fully dissolved. Do not shake. The reconstituted solution should be clear and colorless.

A 10 mg vial with 5 mL gives 2,000 mcg/mL (2 mg/mL). A common 500 mcg dose requires 0.25 mL (25 IU on a U100 insulin syringe). For an initiation dose of 250 mcg, the required volume is 0.125 mL (12.5 IU). Use 27–30 gauge insulin syringes for subcutaneous administration. Common injection sites are the abdomen and upper thigh. Administer approximately 1–2 hours before intended sun exposure or UV light exposure in tanning research, as UV exposure potentiates the melanogenic effect.

Melanotan II research typically begins with a low initiation dose to assess tolerability before increasing to target doses, due to the dose-dependent side effects (nausea, flushing, spontaneous erections) that occur with higher doses. Protocols published in clinical research studies and commonly referenced in the research community use:

Initiation doses of 0.25 mg (250 mcg), administered in the evening to minimize nausea (which tends to be worse on an empty stomach). After assessing tolerability, doses are increased to 0.5 mg, then up to a typical range of 0.5–1.0 mg per administration. Frequency ranges from daily dosing during loading phases to every-other-day maintenance dosing once desired pigmentation levels are reached.

In the Arizona University clinical tanning studies (Dorr et al., 1996, JAMA), subjects received daily doses of 0.16 mg/kg of MT-II for several weeks. For a 70 kg subject this corresponds to approximately 11.2 mg per day — far above what most modern research protocols use, suggesting the compound is active at much lower doses and that earlier trials used suprapharmacological doses. More recent research uses significantly lower doses in the range described above.

Lyophilized Melanotan II is a cyclic peptide with good dry storage stability. Store at 2–8°C in the refrigerator and keep away from light. Do not freeze. Once reconstituted in bacteriostatic water, store at 2–8°C and use within 30 days. Light sensitivity of the reconstituted solution is higher than the dry form; store in an amber vial or in a dark location to minimize UV-induced degradation. The reconstituted solution should remain clear and colorless; discard if any coloration or cloudiness appears.

The most common adverse effects reported in Melanotan II research are nausea, flushing (particularly of the face and neck), fatigue, and spontaneous erections in males — all dose-dependent and generally more pronounced with higher doses and on an empty stomach. The nausea typically diminishes with continued use as tolerance develops. Dermatological concerns include irregular darkening of existing moles and possible new mole formation, which have been reported in case studies; regular skin monitoring is therefore important in any MT-II research protocol. Hyperpigmentation occurs in a dose-dependent fashion and can affect non-sun-exposed areas. This compound is a research chemical with no regulatory approval; all use is strictly for laboratory investigation.