Melanotan II

Overview

Melanotan II (MT-II) was developed in the 1990s by researchers at the University of Arizona (including MacEwen, Hruby, and Dorr) as a highly stable, "superpotent" cyclic analog of the naturally occurring alpha-melanocyte-stimulating hormone (α-MSH) [1]. The original goal was to create a peptide capable of inducing melanogenesis (skin darkening) without UV exposure, with the intent of developing a prophylactic treatment against skin cancer.

Early Phase I trials delivered an unexpected finding: beyond tanning, MT-II produced robust pro-erectile and libido-enhancing effects. Subsequent Phase II trials formally confirmed these effects, generating significant research interest in the compound as a potential treatment for erectile dysfunction [1][2].

Clinical development was ultimately abandoned due to a non-selective receptor binding profile that produced severe and unacceptable side effects. Researchers subsequently developed Bremelanotide (PT-141), a more selective analog, which achieved FDA approval in 2019 as Vyleesi for hypoactive sexual desire disorder in premenopausal women [4].

Mechanism of Action

• MC1R (skin): Stimulates melanocytes to produce eumelanin, causing progressive skin darkening without UV exposure [1].

• MC3R / MC4R (hypothalamus): Triggers pro-erectile signaling via nitric oxide (NO) pathways, increases sexual desire, and exerts anorexigenic (appetite-suppressing) effects [4][5].

• Non-selectivity: Because MT-II engages all four receptor subtypes rather than targeting a specific one, it cannot produce its desired effects without simultaneously triggering widespread systemic responses: nausea, cardiovascular effects, spontaneous erections, and more.

Clinical Trials

MT-II progressed through Phase I and Phase II human trials between 1996 and 2000, producing some of the most striking efficacy results seen in erectile dysfunction research at the time. Development was not halted for lack of effect; it was halted because the side effects were deemed unacceptable for mainstream clinical use.

Dosing & Administration

• Phase I/II clinical trials (ED): Single subcutaneous injection at 0.025 mg/kg (~1.75 mg for a 70 kg subject).
• Wellness/cosmetic clinic pattern (tanning): Microdoses of 100–250 mcg SC daily to build pigmentation, followed by maintenance doses once or twice weekly.
• Primary route (clinical trials): Subcutaneous (SC) injection, the only route established in peer-reviewed clinical data.
• Other routes: Intranasal and sublingual tablet formulations are compounded and sold by research vendors; these routes lack controlled clinical validation.

Safety Risks & Regulatory Status

• FDA Status: Not approved. Melanotan II was never granted FDA approval. Clinical development was formally discontinued after Phase II trials.
• Bremelanotide (PT-141 / Vyleesi): The selective follow-on compound developed from MT-II research received FDA approval in 2019 for hypoactive sexual desire disorder. It is the only melanocortin-pathway drug currently approved for human use.

Vendor Directory

Vendor list sourced from Finnrick Analytics – Melanotan II page. Data collected February 2026. Tables are split by formulation; vendors without public pricing are listed separately below.

SC Injection: Lyophilized Powder

Nasal Spray

Sublingual Tablets (200 mcg / tablet)

No Public Pricing

These vendors carry or have carried Melanotan II but do not list public retail prices, require login, or are temporarily unavailable.

* Data Notes: Data collected February 2026. All products sold strictly for in-vitro research purposes. Prices subject to change. * Sale price active at time of data collection; verify current pricing before purchasing.