Melanotan II: The Record on a Tanning Peptide

What was actually tested in people?

Melanotan II is a cyclic analog of alpha-melanocyte-stimulating hormone and a non-selective melanocortin agonist. Across five name variants PubMed returns 360 indexed records, 119 tagged Humans, 4 under the clinical-trial publication type and 1 under the randomized type ^[5]. All four were opened, and every one was published between 1996 and 2000; re-measured in September 2026 the counts are identical, and the names combined with tanning terms return 23 records of which exactly 1 carries a trial publication type ^[13].

That one is the 1996 pilot phase I study: three normal male volunteers, subcutaneous doses escalated from 0.01 mg/kg to 0.03 mg/kg in two subjects and to 0.025 mg/kg in the third, two subjects with measurably increased pigmentation a week after dosing ended, and spontaneous erections lasting one to five hours after each dose, which the authors noted in passing ^[1]. The tanning record of the compound is that paragraph. The three trials that followed pursued the incidental finding instead: a double-blind placebo-controlled crossover in 10 men with psychogenic erectile dysfunction, in which 8 of 10 developed erections and the mean duration of tip rigidity above 80% was 38.0 minutes against 3.0 on placebo (p = 0.0045) ^[2]; a summary of the human melanocortin program ^[3]; and a crossover in 10 men with organic erectile dysfunction, in which 12 of 19 injections produced erections against 1 of 21 placebo doses, mean rigidity duration 45.3 against 1.9 minutes (P = 0.047), with severe nausea after 4 of 19 injections ^[4].

Then the trials stopped. The compound's development lineage continued under a different name, and the monograph records what the marketed product has been sold for since; the trial record prints the four records beside every other count in the index.

What has been published since the trials stopped?

Case reports. The five names combined with the case-report publication type return 23 records, 21 of them tagged Humans; combined with the term melanoma they return 17 records, 9 of them case reports; the filters were proved live against a control term in the same run, and the reference records the counts ^[13].

The named cases are specific. Melanoma has been reported in association with use ^[6]. Renal infarction has been reported, with a review of the literature attached ^[7]. Priapism has been reported ^[8]. A 39-year-old man who injected 6 mg bought over the Internet, six times the starting dose he had been told, presented two hours later with a heart rate that peaked at 146, diffuse muscle tremor and a creatine kinase that rose to 17,773 IU/L, spent three days in intensive care for rhabdomyolysis, and the substance he injected was confirmed by mass spectrometry to be Melanotan II ^[9].

A case report establishes association rather than cause, and nothing here claims more. The shape of the file is the finding: the published benefit for the marketed use is one paragraph about two men in 1996, and the published harm since is a case-report literature that has kept growing since the trials ended ^[13].

What did removal from Category 2 change?

Less than it is reported to have changed. Melanotan II sat in Category 2 of FDA's interim section 503A bulks list, the category for substances that raise significant safety risks, and left it in April 2026 when its nominators withdrew the nomination; it was not added to Category 1 ^[11], and on the list FDA published on May 14, 2026 it appears in no category at all ^[10]. It is not among the seven peptides on the July 2026 committee agenda that the vote ledger records, so no panel has weighed its dossier, and the category 2 removal table sets out why leaving that category confers nothing.

The safety finding did not leave with it. FDA continues to publish the entry among substances nominated but withdrawn: compounded drugs containing Melanotan II may pose a risk for immunogenicity, and published case reports discuss serious adverse events including melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome and priapism ^[11]. In April 2020 FDA had already warned a compounding pharmacy that products compounded with Melanotan II and twenty-one other substances were not eligible for the exemptions in section 503A(a) ^[12]. Drugs@FDA holds no application under the name, while the identical query returned an approved application for a control term in the same run ^[14]. A substance whose safety statement still stands and whose nomination no longer does is further from lawful compounding than it was, not closer; the research-only page explains why, and the nomination tracker files it by that outcome.

How does it differ from the approved relative?

The erection findings of 1998 and 2000 were not wasted; they were carried forward under a different molecule. PT-141, bremelanotide, is a metabolite of Melanotan II, and its sponsor completed the development program this compound never had: an approved product for one indication in premenopausal women, with a label that states what it does not cover. The PT-141 review reads that record and cites the approval letter and the label. The two molecules share a receptor family, a class in this index, and a history, and they share nothing in regulatory status.

What is sold under the name?

Research-use-only chemical supply, produced and sold outside pharmacy licensure and prescriber oversight, and bought as the patient in the rhabdomyolysis case bought his, over the Internet, in an amount no label had set ^[9]. The research-use-only entry sets out what that posture does and does not mean, and the melanocortins class collects the molecules that share this receptor family. What a buyer receives under this name is a substance with no tanning trial, a standing FDA safety finding, and a case-report file counted above rather than characterized.

Elsewhere in this index