DOSAGE RESEARCH CONTEXT

What the studies actually used

There is no approved dose of Melanotan II anywhere. The only controlled human dosing data comes from three small University of Arizona studies: a 1996 tanning pilot in three healthy men (0.01–0.025 mg/kg subcutaneous, escalated over two weeks) and two 1998–2000 erectile dysfunction crossover trials (0.025 mg/kg subcutaneous, single dose per visit). Those are the published dose points — they describe what was studied in what species at what quantities, not a recommendation. The case report literature adds a different kind of dosing data: what happens at doses far above the research range (6 mg, 10 mg), and what happened to one man at a 2 mg dose he'd taken repeatedly for six years. None of this is a protocol.

Human Trial Doses: The Controlled Record

The controlled human dosing record for MT-II is thin. Three studies used human subjects; all three were conducted at the University of Arizona between 1996 and 2000.

The 1996 Dorr et al. phase I tanning pilot used doses of 0.01–0.025 mg/kg subcutaneous in three healthy male volunteers, administered in escalating fashion over two weeks ^[1]. At 0.025 mg/kg — the highest dose in the phase I trial — measurable pigmentation was observed in two of three subjects. The same dose produced spontaneous penile erection in one subject lasting one to five hours. This is the published lowest effective human dose for MT-II tanning activity. The trial had no placebo arm and enrolled three subjects.

The 1998 and 2000 Wessells et al. erectile dysfunction crossover trials both used 0.025 mg/kg subcutaneous as the single trial dose ^[2][3]. This was not a dose-finding study — it used the dose already established as tolerable in the phase I tanning pilot. Both trials were single-dose crossover designs: one injection per crossover visit, outcomes measured within the session. Neither study examined repeated dosing, long-term effects, or cumulative exposure.

The half-life of MT-II in human plasma is approximately one hour post-injection, as reported in the Arizona research program literature ^[1]. This contrasts sharply with native α-MSH, which is degraded in plasma within one to two minutes. The cyclic lactam structure responsible for MT-II's stability is the same structural feature that gives it approximately 1,000-fold greater potency than the parent peptide in melanotropic bioassays. Duration of biological effect — particularly pigmentation and pro-erectile signaling — substantially outlasts the plasma half-life.

No dose-finding, dose-escalation, or dose-response studies in humans have been published beyond the three Arizona trials. No large randomized controlled trials exist. Clinical development of MT-II was discontinued before phase III; bremelanotide (the derived compound) carried the program forward through FDA approval for a different indication.

Rodent Model Doses: A Different Scale Entirely

Rodent dosing for MT-II in the research literature covers several distinct experimental contexts, all using routes and doses that have no direct human translation.

In the nucleus accumbens microinjection feeding model (Eliason et al. 2022) ^[4], bilateral injections of 0.1, 0.3, and 1 nmol per side were used in male C57BL/6J mice. These are intracerebral doses — not systemic doses — and the route (bilateral stereotaxic microinjection into a specific brain nucleus) is a research methodology for isolating circuit-level effects, not a translatable administration method.

In the NPY antagonism model (Raposinho et al. 2003) ^[6], male Sprague-Dawley rats received 15 nmol/day MT-II via intracerebroventricular infusion for seven days, co-infused with 5 nmol/day NPY. Again, the ICV route is a rodent research method, not a translatable one.

In the nerve regeneration studies (Ter Laak et al. 2003) ^[7], male Wistar rats received 2, 20, or 50 μg/kg subcutaneous every 48 hours. The 20 μg/kg dose produced the significant sensory recovery finding. Extrapolated naively to human weight, these are far below the 0.025 mg/kg doses used in the human trials — but the extrapolation is not meaningful because the species pharmacokinetics differ substantially.

In the brown adipose thermogenesis model (McMillan et al. 2021) ^[5], female PACAP-deficient mice received daily peripheral MT-II injections for three weeks. The paper reports this as 'peripheral injection'; dose in mg/kg is not specified in the abstract.

In the chronic unpredictable stress model (Inozemtseva et al. 2024) ^[15], male Sprague-Dawley rats received 60 nmol/kg body weight daily intraperitoneally for the duration of the CUS protocol. 60 nmol/kg intraperitoneal in a rodent is a research dose in an animal model; it is not a human clinical dose and cannot be directly translated.

In the visceral adipose tissue model (Strader et al. 2007) ^[8], diet-induced obese mice and rats received peripheral injection; dose is not specified in the abstract, and the finding involved pair-fed controls, so the metabolic mechanism study was designed around caloric equivalence rather than dose-response.

Routes Studied and Formulation Notes

Melanotan II has been studied via the following routes across the peer-reviewed literature:

Subcutaneous injection is the only route used in human clinical studies, both the controlled trials and the case reports ^{[1][2][3][9][10][11][12][13][14]}. All phase I/II human data derive from subcutaneous delivery.

Intraperitoneal injection has been used in rodent models where systemic absorption with precise dose control is needed ^[5][15]. This is a standard rodent research route with no human equivalent.

Intracerebroventricular infusion has been used in rat feeding and NPY antagonism models ^[6]. This is a specialized research route requiring stereotaxic surgery; it allows study of central CNS effects in isolation from peripheral pharmacokinetics.

Bilateral intracerebral microinjection into specific nuclei (nucleus accumbens) has been used in mouse feeding models ^[4]. Same research-methodology context as ICV.

Intranasal delivery has been studied with bremelanotide — the derived compound — not with MT-II itself. The nasal route for MT-II proper has not been the subject of published controlled studies ^[17].

Formulation notes from the research literature: lyophilized powder form is stated to be stable at room temperature for months when kept dry; reconstituted solution should be refrigerated ^[1]. Reconstitution of lyophilized MT-II by lay users introduces contamination risk; regulatory seizure analysis of internet-purchased MT-II has found variable purity (noted in compliance literature). MT-II is approximately 1,000-fold more potent than native α-MSH in melanotropic bioassays — meaning dose measurement error has amplified consequences relative to the parent peptide.

There is no approved dosing protocol for MT-II in any jurisdiction. MT-II has no approved therapeutic indication in the US (FDA), EU (EMA), UK (MHRA), or Australia (TGA). The doses in this section are a summary of what was used in published research; they are not a dosing guide.

What the Case Reports Add to the Dosing Picture

The toxicology case reports are, in an unintended way, dosing data — specifically, data on what happens at doses substantially above the research trial range.

The rhabdomyolysis case (Nelson et al. 2012) ^[9] involved 6 mg subcutaneous — a dose that, for a 75 kg adult, represents approximately 0.08 mg/kg, well above the 0.025 mg/kg research ceiling. The outcome was ICU admission with CPK over 17,000 IU/L.

The renal infarction case (Peters et al. 2020) ^[18] also involved 6 mg subcutaneous, with CT-confirmed right renal infarction affecting approximately 50% of the kidney.

The priapism case resulting in permanent erectile dysfunction (Mallory et al. 2021) ^[11] involved 2 mg subcutaneous — a dose within the range commonly reported in user survey data ^[16][19] — in a 55-year-old man with six years of prior MT-II use. This case is notable precisely because 2 mg is not an overdose in the sense of the rhabdomyolysis case; it is a dose-after-repeated-exposure finding. The resulting ischemic priapism lasting 30 hours required surgical decompression, and permanent erectile dysfunction with corpora fibrosis followed.

The overdose priapism case (Devlin et al. 2013) ^[10] involved 10 mg subcutaneous, approximately 40 times higher than the controlled trial dose at average body weight.

The melanoma case (Hjuler and Lorentzen 2014) ^[12] involved self-administration over three to four weeks with concurrent sunbed use; dose not specified.

The oral mucosal pigmentation case (Bonchev 2026) ^[14] involved 0.4 mg per injection over 32 injections totaling 12.8 mg over 64 days — a cumulative exposure well beyond anything in the controlled trial literature, which used single-dose or two-week short-course protocols.

The dosing record across case reports and controlled trials together suggests: the gap between controlled-trial doses (0.01–0.025 mg/kg) and doses associated with serious adverse events (0.08 mg/kg and above, or cumulative exposures far beyond trial durations) is narrower than lay-user discourse typically acknowledges. The 6 mg and 10 mg doses in the toxicity cases are not laboratory errors — they represent what happens when bulk lyophilized powder is self-dosed without precision equipment.