MT2 Dosage in the Research Literature — Melanotan 2 Protocols and Pharmacokinetics

This page documents the Melanotan 2 (MT-II) and MT2 dosage protocols described in published research. All figures are from primary literature sources. This site does not provide human use recommendations. MT-II has not been approved by any regulatory agency for any indication.

Doses Studied in the Research Literature

The published human trial record covers a narrow dose range. The Dorr 1996 Phase I study administered 0.01 mg/kg subcutaneously — approximately 0.7 mg for a 70 kg subject — as the initial dose, with escalation to 0.025 mg/kg across five administrations over ten days.^[1] Measurable pigmentation was observed in two of three subjects; spontaneous erections lasting 1–5 hours, nausea, and somnolence were the principal adverse effects.

The Wessells 1998 erectile function study used 0.025 mg/kg subcutaneously in ten men with psychogenic erectile dysfunction.^[2] The 2000 Wessells expansion confirmed this dose across 20 subjects^[3]; severe nausea was reported in 12.9% at 0.025 mg/kg, placing this dose near the maximum tolerated dose in the study population.

Dose	Route	Species	Study / Reference
0.01–0.025 mg/kg	Subcutaneous	Human	Dorr 1996, Wessells 1998/2000 ^[1]^[2]^[3]
20 mcg/kg q48h	Subcutaneous	Rat	Ter Laak 2003 ^[13]
225 ng total ICV	Intracerebroventricular	Mouse	Heijboer 2005 ^[12]
0.1–1 nmol bilateral	Intra-NAcc	Mouse	Eliason 2022 ^[6]

Melanotan 2 Half-Life and Pharmacokinetics

Stylized plasma concentration decay curve illustration — Stylized plasma concentration decay profile — terminal half-life approximately 1 hour in rat IV pharmacokinetic studies.

Plasma half-life is approximately 1 hour based on available pharmacokinetic data. Ugwu 1994 used radiolabeled HPLC and bioassay methods to quantify MT-II in rat plasma following IV administration at 0.3 mg/kg.^[16] Both methods yielded correlated plasma profiles (r=0.90, p<0.001). The terminal half-life calculation was sensitive to sparse beta-phase sampling, so the precise value carries some uncertainty. Oral bioavailability in the rat was 4.6%, reflecting peptide bond degradation in the gastrointestinal tract.

For comparison, the structural parent alpha-MSH has a plasma half-life of approximately 10–15 minutes in rodents — the cyclic backbone and D-Phe7 substitution of MT-II confer roughly a 4–6 fold metabolic stability improvement. The related linear compound MT-I (afamelanotide) shows a beta-phase half-life of 0.8–1.7 hours in human subcutaneous pharmacokinetic studies.

A critical pharmacokinetic characteristic: melanogenic effects persist for weeks to months after plasma clearance. Once tyrosinase is upregulated and eumelanin is deposited in melanocytes and transferred to keratinocytes, pigmentation is retained until the natural turnover of skin cells. This biological persistence explains why tanning effects in the Dorr study continued beyond the active dosing period.^[1]

Onset of Action in Research Studies

Transient effects — nausea, flushing, spontaneous erections — emerged within 30–60 minutes of subcutaneous injection in the Dorr 1996 human trial.^[1] This is consistent with the compound's plasma pharmacokinetics: the peptide reaches effective concentrations in blood and central compartments within the first hour after subcutaneous administration. Pigmentation changes were measurable at 2–3 weeks. The plasma half-life is approximately 1 hour in available pharmacokinetic data; the melanogenic effect persists far beyond plasma clearance because eumelanin already synthesized in melanocytes does not depend on continued peptide presence.

Duration of Melanogenic Effect in Research Studies

In the Dorr 1996 study, pigmentation increases persisted beyond the active dosing period.^[1] Formal maintenance decay timelines have not been characterized in controlled human studies. Animal models suggest melanin accumulation in the epidermis gradually fades over weeks to months following cessation of MC1R stimulation, as pigmented cells naturally exfoliate and melanogenesis slows to baseline rate. The biological persistence of tanning effects is substantially longer than the plasma half-life of MT-II (~1 hour) because pigment production and deposition is a cellular process rather than a pharmacokinetic one.

Administration Routes in Research Protocols

Animal studies use subcutaneous, intravenous, intracerebroventricular, and intranasal administration routes. The Dorr 1996 and Wessells 1998/2000 human trials used subcutaneous injection^[1]^[2]^[3]; this is the only route with published human pharmacodynamic data.

Intranasal administration has been studied in rodent models. Paiva 2017 compared IV and intranasal MT-II in rats, finding that IV administration markedly induced Fos expression in oxytocin-containing neurons of the supraoptic and paraventricular hypothalamic nuclei, while intranasal administration produced no detectable central Fos induction.^[15] This suggests that intranasal delivery does not achieve the same central pharmacological profile as parenteral routes, likely due to inadequate central bioavailability via nasal mucosa in rodents.

Intracerebroventricular administration is used in mechanistic research (Heijboer 2005, Raposinho 2003) to isolate central receptor effects from peripheral ones.^[12] This route is not applicable outside of controlled preclinical studies.

Reconstitution in Research Settings

Published research protocols describe reconstitution in sterile water or bacteriostatic saline for subcutaneous administration studies. MT-II is typically provided as lyophilized (freeze-dried) powder for research use; the lyophilized form is stable at room temperature for short periods and at 4°C or below for extended storage, based on standard peptide stability principles. Specific reconstitution procedures should be drawn from the methodology sections of published protocols — the Dorr 1996 paper describes preparation details for the Phase I study. Oral bioavailability is 4.6% in rats^[16], which is why subcutaneous administration is the route used in all clinical-stage MT-II human trials.

How Long Does Melanotan 2 Take to Produce Tanning?

In the Dorr 1996 Phase I study, five subcutaneous doses over ten days produced reflectance-measured pigmentation increases within 2–3 weeks in two of three subjects.^[1] Individual response varied substantially with baseline Fitzpatrick skin type; lighter skin types showed greater relative change. Measurable pigmentation was present at the first post-dosing assessment; peak pigmentation and exact timeline were not formally quantified in the three-subject pilot design.