Melanotan II

Areas of active research — not promised effects

Each tag links to other compounds with research into that goal. Research use only: these are areas of study, not human-use claims.

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MT-II is not an FDA-approved drug for any indication. It was originally placed on the FDA 503A Category 2 list (bulk drug substances presenting significant safety concerns that may not be compounded). In April 2026, MT-II was among 12 peptides removed from Category 2 after withdrawal of nominations. However, removal from Category 2 does not confer Category 1 status or permit compounding — MT-II cannot be lawfully dispensed as a compounded prescription product until the Pharmacy Compounding Advisory Committee (PCAC) completes its evaluation and FDA issues a final determination. The PCAC is expected to convene for MT-II review before February 2027. Until then it remains in a regulatory grey zone: not a scheduled controlled substance, but not lawfully compoundable or marketed for human use. Legitimate sale is restricted to licensed research institutions for non-clinical RUO purposes.

Transparent blend · bci-1.0 · never paid-placement

Primary name

Melanotan II

Origin

Melanotan II (MT-II; CAS 121062-08-6) is a synthetic, cyclic analogue of alpha-melanocyte-stimulating hormone (α-MSH), itself derived from pro-opiomelanocortin (POMC). It was developed at the University of Arizona in the late 1980s–early 1990s as a superpotent, protease-resistant melanocortin-receptor agonist by cyclising and modifying the core heptapeptide sequence of α-MSH to confer greater receptor affinity and metabolic stability compared with the native linear peptide.

Registry IDs

PubChem CID

92432

CAS

121062-08-6

InChIKey

JDKLPDJLXHXHNV-MFVUMRCOSA-N

ChEMBL

CHEMBL430239

Molecular formula

C50H69N15O9

Molar mass

1024.2 g/mol

Monoisotopic

1023.54026884 Da

InChIKey

JDKLPDJLXHXHNV-MFVUMRCOSA-N

Appearance

White to off-white lyophilised powder

Solubility

Soluble in water and dilute aqueous acid (e.g. 0.1–1% acetic acid); limited solu…

Sequence not available in current seed.

Stability: Moderately stable as lyophilised solid under cold, dry, dark conditions; susceptible to oxidation and proteolytic degradation in solution; cyclic lactam backbon

Vial sizes

10 mg · 5 mg

Purity grades

≥98% HPLC

Salt forms

Free base (primary)

• GHS hazard class on file
• PPE & spill response
• Disposal guidance
• Not-for-human-consumption posture

How much research exists, and of what maturity — never a verdict on whether it works.

Mechanism of action

• MT-II binds and activates multiple melanocortin receptor subtypes with a rank-order affinity of MC1R ≥ MC4R > MC3R > MC5R; it has negligible activity at MC2R (the ACTH-selective receptor)
• At MC1R on epidermal melanocytes, receptor coupling to Gs/adenylyl cyclase elevates intracellular cAMP, activates protein kinase A, and upregulates the MITF transcription factor, shifting melanin synthesis toward the darker eumelanin pigment and increasing overall melanin output
• At MC4R expressed predominantly in hypothalamic and limbic neurons, agonism modulates the central circuits governing appetite (producing anorexigenic effects), energy homeostasis, and sexual arousal — accounting for the pro-erectile and pro-sexual-motivation effects observed across preclinical and early clinical studies
• Central MC3R and MC4R activation also accounts for the transient nausea, yawning, and stretching that are characteristic side-effects

Pharmacokinetics (ADME)

Half-life

~0.5–2 hours (subcutaneous; extrapolated from early Phase I human data and structural analogy to Melanotan-I)

Clearance

Primarily proteolytic degradation and renal excretion; <4% of dose recovered intact in urine in analogous melanotropin studies

PK–PD note: Direct MT-II human PK data are sparse; the 1996 Phase I pilot study (Dorr et al., ScienceDirect; outside gathered PMID list) administered 0.01 mg/kg SC and documented tanning and erectile responses bu…

Reading the evidence

• Evidence quality and gaps vary by application — see the cited grades above.
• Indexed-article counts span all evidence tiers, not only completed human trials.
• No first-party human-dosing, efficacy, or benefit claims are made here.

Key reviews & evidence-gap sources

• Brennan, Wells & Van Hout 2014 — 'An unhealthy glow? A review of melanotan use and associated clinical outcomes' (Performance Enhancement & Health 3(2):78-92) — Narrative review of melanotan I/II literature to 2014; 18 clinical trials + 21 clinical case presentations screened; concludes long-term health outcomes remain undocumented. The anchor for literatureSize.basis.
• Wessells et al. 1998 (J Urol 160(2):389-93) — double-blind, placebo-controlled crossover RCT, psychogenic erectile dysfunction, n=10 — Verified against primary PubMed. Attributed early-phase research finding; RUO — not an FDA-approved indication or a dosing recommendation.
• Wessells et al. 2000 (Urology 56(4):641-6) — double-blind, placebo-controlled crossover RCT, organic erectile-dysfunction risk factors, n=10 — Distinct study from the 1998 paper (different population/journal/results). Verified against primary PubMed. Attributed research finding, RUO.
• Dorr et al. 1996 (Life Sci 58(20):1777-84) — pilot phase-I pigmentation study, n=3 (single-blind, non-randomized, alternating-day placebo-controlled) — Verified against primary PubMed. Blinded/placebo-controlled but not a strict RCT — counted here, not in completedHumanRcts. Small n=3 pilot; keeps evidence at early-human maturity.
• O'Mahony et al. 2024 (Br J Dermatol 191:Suppl_1, i72) — systematic review of social media and melanotan (the 'Barbie drug') — Conference-abstract-form systematic review; found social media rarely portrays MT-II negatively despite documented harms.
• Orr et al. 2025 (J Eur Acad Dermatol Venereol; doi:10.1111/jdv.20144) — 'The Barbie Drug: marketing and perceptions of melanotan on social media' — Content analysis; among MT-2 posts that mentioned skin cancer, roughly one in three falsely claimed the drug protects against skin cancer — there is no evidence MT-II is photoprotective.
• Peters, Hadimeri & Wahlberg 2020 (CEN Case Rep 9:159-61) — Melanotan II as a possible cause of renal infarction (review + case report)
• Mallory, Lopategui & Cordon 2021 (Sex Med 9(1):100298; PMID 33460908) — Melanotan tanning injection: a rare cause of priapism — Peer-reviewed case report; ischemic priapism after a 2 mg dose required surgical intervention. One of several MT-2 priapism case reports (BMJ Case Rep 2019; Clin Toxicol 2013).
• Case report (2025, PMC) — Changes in Oral Mucosa Associated with Melanotan II Injections

1 registered trial — 1 currently recruiting.

Phase 2
NCT07437560
Melanotan II (MT-II) as an Adjunct to NB-UVB Phototherapy for Repigmentation in Stable Nonsegmental Vitiligo

RECRUITING

Summary (literature)

The most consistently reported acute adverse effects of MT-II across early human studies are nausea and vomiting (reported in the majority of subjects at active doses), facial flushing, and spontaneous penile erections beginning 1–5 hours after injection. At higher doses, yawning…

WADA status

Prohibited at all times (in- and out-of-competition) under the WADA 2026 Prohibited List, Section S2 — Peptide Hormones, Growth Factors, Related Substances and …

Dominant research route: Subcutaneous injection is the only route used in every completed human study located — a 1996 dose-escalation pigmentation pilot and 1998/2000 double-blind, placebo-controlled crossover trials for erectile dysfunction — and is the near-universal route in a 2024 qualitative study of community self-administration. Animal/mechanistic work has separately used intravenous (the PK reference route, rats), intraperitoneal (peripheral metabolic/thermoregulatory studies, mice/rats) and topical (a local mouse melanoma model). No human oral or intranasal pharmacokinetic study of MT-II itself was located.

The route used in every published human study: a 1996 single-blind, placebo-controlled dose-escalation pilot (3 healthy male volunteers, 0.01–0.03 mg/kg) and 1998–2000 double-blind, placebo-controlled crossover trials in men with erectile dysfunction (0.025 mg/kg; n=10 per arm).

Bioavailability: No formally published human SC pharmacokinetic parameters (Cmax, half-life) for MT-II itself were located — the phase-I pilot reported pigmentation/physiologic responses, not plasma PK. A ~33-minute human half-life circulates on secondary/vendor pages but could not be traced to a primary source and is NOT included here (do not conflate with the separately-published PK of the distinct linear analog melanotan-I/afamelanotide).

Every completed human study of MT-II dosed it subcutaneously; a 2024 qualitative interview study of 28 community users likewise found self-injection via insulin needles to be the near-universal real-world route. No human dosing protocol implied.

Characterized in a rat pharmacokinetic study (0.3 mg/kg IV bolus, male Sprague-Dawley rats) comparing HPLC vs a radioreceptor bioassay for plasma MT-II quantification. Animal-only; no published human IV PK study of MT-II was located.

Bioavailability: 100% bioavailable by definition (reference route). Cmax, AUC, clearance, MRT and terminal half-life were determined in rats; the two assay methods gave somewhat different terminal-half-life estimates, so no single authoritative human-equivalent half-life is reported.

Used in animal studies purely as the pharmacokinetic reference/comparator route, not a human administration route.

Widely used as the 'peripheral' comparator route in mouse/rat metabolic and thermoregulatory mechanism research — e.g., IP MT-II causes transient hypothermia via a mast-cell-dependent pathway in mice, and reduces visceral fat mass in rats via lipid mobilization. Animal-only; not a human route.

Bioavailability: No dedicated IP pharmacokinetic characterization was located; IP dosing in these studies probes peripheral-vs-central mechanisms and downstream metabolic/thermoregulatory effects, not PK parameters.

A laboratory-animal administration route, cited only to describe how preclinical mechanistic/metabolic work was conducted; no human protocol implied.

A single located preformulation/pharmaceutics study (Lan et al. 1994, J Pharm Sci 83(8):1081-4; PMID 7983590) measured MT-II solution-degradation kinetics and reported an oral bioavailability of 4.6% in the rat. No human oral study of MT-II was located.

Bioavailability: Degradation in solution follows first-order kinetics, fastest at higher temperature/phosphate-buffer concentration, most stable near pH 5. The measured 4.6% rat oral bioavailability is low but non-zero; the authors treat it as a rationale for further oral-formulation research, not as evidence supporting oral dosing.

[Verification corrected: the first pass flagged this figure as 'could not be independently re-confirmed via direct fetch.' It IS directly verifiable — NCBI's E-utilities efetch for PMID 7983590 returns the verbatim abstract '...the observance of a bioavailability of 4.6% in the rat...' — so the unverified caveat is dropped; the figure is stated as a primary-sourced rat preclinical value. 'Oral bioavailability' is the standard PK reading of that phrase.] All documented human and community use of MT-II is by injection, not oral; no human oral efficacy or dosing is implied.

No published clinical or pharmacokinetic study of intranasal MT-II in humans was located. It is nonetheless widely sold and community-used as a needle-free 'nasal spray' alternative to injection.

Bioavailability: No published bioavailability/PK data for intranasal MT-II in any species was located. Vendor/community sources assert lower, more variable bioavailability than SC injection and recommend a higher nasal dose to compensate, but this is not backed by any comparative study of MT-II itself.

A predominantly marketed/community route. Its rationale is extrapolated from general intranasal-peptide delivery science and from bremelanotide/PT-141 — a chemically DISTINCT, metabolite-derived MT-II analog independently developed by Palatin Technologies and FDA-approved (as Vyleesi) as a SUBCUTANEOUS injection, not intranasal, after an earlier intranasal program was halted in 2007 — not demonstrated for MT-II itself. No human dosing protocol implied.

Studied in a mouse melanoma model: daily topical MT-II (0.1 mL of 1 µg/mL in PBS, 10 days) on C57BL/6 mice bearing established B16-F10 tumors reduced tumor volume ~50% vs control, via apoptosis induction, reduced proliferation/neovascularization and COX-2/PGE2 suppression. A preclinical local-oncology finding, not a tanning-cosmetic human study.

Bioavailability: Systemic absorption through skin was not the measured endpoint — the study reports local tumor-tissue molecular/histological effects, not plasma PK. Cosmetic-formulation patent literature describes topical MT-II tanning compositions, but no peer-reviewed human topical-absorption or tanning-efficacy study was located.

A local-delivery, animal oncology-context finding — not evidence of topical tanning efficacy, systemic delivery, or any human protocol.

Animal & human figures are kept visibly separate so studied animal doses are never misread as human guidance.

Sorted A–Z by vendor — never by price

Weekly median $/mg from the live vendor crawl.

Researched storefront prices, bucketed

p25 $3.40 · median $3.90 · p75 $4.65 · 11 researched vendors

Legit, COA-backed band: $3.50–$6.50/mg.

Value rule: don't just buy the cheapest — a price under $3/mg is a red flag. Pair price with COA and independent-test grade.

Estimated cost of research (10 mg)

Vial (best researched price)

$30

Bacteriostatic water (generic estimate)

$6

Syringes / supplies (generic estimate)

$12

What each test proves — general guidance, plus this compound's researched purity data

Purity on the current market (researched)

Reputable US/UK research-vendor market clusters roughly 97.7–99.95% HPLC purity (Finnrick aggregate: 140 Melanotan II samples across 34 vendors, Feb 2025–Mar 2026, 5th–95th percentile). By contrast, an independent peer-reviewed analysis of gray-market injectable vials (Breindahl et al. 2015, Drug Testing and Analysis; PMID 24771717) found unidentified impurities of 4.1–5.9% (LC-UV) in vials from 2 of 3 online shops, with the third below the quantification limit — quality diverges sharply between the reputable-vendor and outright-illicit ends of this compound's unusually broad grey market. [Verification: impurities reported as '%' (LC-UV area at 218 nm), not 'by mass' — the earlier 'by mass' gloss is dropped per the primary abstract.]

Independent labs cited for this compound

No formal FDA Class I/II/III product recall of a Melanotan II product was identified (FDA recall/enforcement resources, July 2026). As an unapproved drug sold outside the regulated supply chain — including via non-pharmacy channels such as tanning salons, gyms, and social media — FDA/DOJ/TGA/MHRA action instead takes the form of warning letters, import detention, infringement notices, and criminal prosecution rather than a classified recall. Reported honestly as an empty recall result, not invented.

Buyer red-flag checklist

• Sold under a cosmetic/novelty framing ('tanning nasal spray', 'tanning injection kit', a branded name that isn't 'Melanotan') specifically to sidestep RUO/research-chemical scrutiny — the exact pattern behind the 2007, 2009 and 2020 FDA warning letters.
• No batch-specific COA (HPLC purity + LC-MS identity) provided on request.
• COA report/task ID does not resolve in the testing lab's own public verification database.
• Direct tanning, libido/erectile, or other human-benefit marketing claims on a site labeled 'research use only' — the specific violation FDA has cited for this compound since 2007.
• Price far below the market band for the stated mg size (consistent with the Breindahl-documented 12–57%-below-label underfill pattern).
• No sterility/endotoxin (LAL) data for a product implied for injection.
• Sold through a non-peptide-vendor channel entirely — tanning salons, gyms, or direct social-media DM sale — the channel UK/Australian regulators flag as least regulated and hardest to verify.

GMP vs research-grade: the chemistry (SPPS + HPLC + MS) is identical — the difference is the quality system.

Underdosing / mislabeling: Underdosing/mislabeling is a documented tail risk in MT-II's gray/black market, not universal among reputable vendors. The only independent academic quantification found (Breindahl et al. 2015, peer-reviewed) tested one 10 mg-labeled vial from each of 3 online shops — all 3 were underfilled at 4.32–8.84 mg (12–57% below label). The Finnrick vendor-testing aggregate (140 samples / 34 vendors) shows advertised-mg fill diverging by up to ±61% from label at the tail. Because MT-II is also sold widely outside the peptide-vendor channel (tanning salons, gyms, unregulated 'nasal tanning spray' brands per UK CTSI), gray-market underdosing/adulteration risk is plausibly higher there than the reputable-vendor aggregates capture. 0.2 is an editorial mid-estimate synthesizing both signals — directional, not a single directly-reported percentage. [A widely-circulated '43% of peptides failed Janoshik purity in 2024' figure is an unverified, industry-wide Layer-B community statistic (not MT-2-specific, no primary Janoshik publication) and is deliberately NOT used here.]

• FDA Import Alert 66-41 provides for Detention Without Physical Examination (DWPE) of unapproved new drugs promoted in the US — the general peptide/research-chemical import control that covers Melanotan II as an unapproved, non-FDA-cleared drug. An RUO/research-chemical or tanning-cosmetic label is not an import exemption; CBP/FDA judge actual marketed/intended use, and MT-II has repeatedly drawn FDA warning letters (2007, 2009, 2020) for tanning/cosmetic marketing on sites selling it as a 'research chemical.'66-41 (unapproved new drugs)
• An RUO label is not an import exemption — CBP judges actual intended use.
• Lyophilized powder is ambient-stable in transit; temperature control needed for > 7-day transit.
• US-warehouse vendors dodge import scrutiny — they cost more but ship more reliably.

Every item dated & sourced

Prohibited at all times (in- and out-of-competition). Melanotan II is not individually named on WADA's Prohibited List; because it has no current approval by any governmental health authority for human therapeutic use, it falls under S0 (Non-Approved Substances) — the same mechanism (definition, not name-by-name enumeration) that covers BPC-157. It is NOT covered by S2 (peptide hormones / growth factors), whose named agents are erythropoietins, gonadotrophins, corticotrophins and GH-type factors, not melanocortin-receptor agonists. [Verification: confirmed by direct text extraction of the official 2026 WADA Prohibited List (zero hits for 'melanotan'/'melanocortin'); the S2 tag seen on some vendor blogs is the error. S0 is a classification DERIVED from the List's definitions, not an explicit per-substance WADA label.]

No granted patents identified in current seed. Composition-of-matter coverage is limited given the peptide's synthetic origin.

• IACUC / IRB research context
• RUO buyer responsibilities & documentation
• Veterinary / alternative-use where lawful
• Jurisdiction-aware "who may lawfully obtain"

What people discuss

Reported concerns — discussion, not established effects

Reading caveats

• Promotional/marketing-toned social content is documented to rarely show Melanotan II negatively despite its real risk profile, skewing the wider online conversation positive relative to the clinical picture (BJD systematic review; The Conversation).
• A 2026 mainstream-media / dermatologist reaction cycle (the 'Barbie drug' coverage) concentrated warning-toned content in this specific window, which can inflate the negative/neutral share of a discourse read timed to this period.
• Demographic mismatch: an interview study of self-reported users found a mean age ~38–39 and >3-in-4 men, introduced via gym/bodybuilding circles years before any tanning-cosmetic trend — an older, longer-tenured base than recent media framing implies.
• Before/after cosmetic-result posts are inherently survivorship-biased — dramatic tans get shared; adverse outcomes (melanoma, priapism) are far less likely to be self-posted.
• Platform-taxonomy gap: TikTok is reported as the dominant real-world venue for MT-2 discovery/promotion in the dermatology literature but is not representable in this sample's platform taxonomy (reddit/youtube/x/bluesky only) — themes here are drawn from adjacent reddit/youtube/x/news-reaction discourse, not TikTok source content itself.
• Review-aggregator scores (WebMD ~4.1/5 over 82 ratings; PeptiRank ~3.3/5 over 49 ratings) come from self-selected purchasers, not a random discourse sample, and likely overweight satisfied users.

Manually researched from reddit, youtube, x— theme weights are research estimates, not live counts; aggregated & de-identified. No individual posts, quotes, or usernames are ever shown.

Relative research / market volume — populated once the activity stream is wired

Inline tooltips for lyophilized, RUO, EU/mg, SPPS, 503A and more.

Toggle plain-language ↔ scientific in the header.

• How to read a COA
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• Understanding evidence grades

Synthetic cyclic melanocortin agonist (MT-II) that stimulates skin pigmentation via MC1R and sexual arousal via MC4R; unapproved in all jurisdictions. Approximately 242 articles are indexed (literature last scanned 2026-05-29). US regulatory status: Not FDA-approved; removed from FDA 503A Category 2 (April 2026); PCAC review pending before February 2027. Research use only.

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