Melanotan 2 and PT-141 act on the same melanocortin receptors, yet they differ in everything that matters most to a buyer. PT-141, also called bremelanotide, is approved as a medicine in the United States under the name Vyleesi. Melanotan 2 is sold as research material and has no approval anywhere. Below is what each of them does, their registration status, and what is still not known about both.
What melanocortin peptides are
These are molecules that act on melanocortin receptors, the system that in our body handles, among other things, skin pigmentation, appetite and sexual behaviour. One receptor switches on pigment production in melanocytes, another sits in the central nervous system. That is where the split between these two peptides comes from: although they share a family, they aim at different effects.
What melanotan 2 does
Melanotan 2 is a synthetic form of the hormone alpha-MSH, melanocyte stimulating hormone. It stimulates pigment production, so the skin darkens without sun exposure. It is an unlicensed and largely unstudied substance, not approved for any medical use in any country.
It should not be confused with afamelanotide, also called melanotan I. Afamelanotide is a medicine used in erythropoietic protoporphyria, a rare blood disorder. It is a different molecule, and the similar name does not carry its approval over to melanotan 2.
Batch quality
The amount of substance in melanotan 2 products on the market has been inconsistent: in tested samples, vials could differ from what was declared. That makes verifying the packaging and the batch certificate a practical matter with this molecule, not a formality.
Reported side effects
Reports fall into those that appear quickly and those described after longer use.
| Short term | Long term |
|---|---|
| Facial flushing, reduced appetite, nausea and vomiting, and in men spontaneous erections with yawning | Melanoma, darkening of moles and new moles appearing, nail discolouration, rhabdomyolysis (breakdown of muscle cells) and encephalopathy syndrome |
One item in the right-hand column deserves a sentence of its own. Darkening of moles is not only a cosmetic effect, because it makes early melanoma harder to spot. A separate risk is contamination of the preparation when it is made up incorrectly, which the guide to reconstitution with bacteriostatic water addresses.
How PT-141 differs from melanotan 2
Bremelanotide is one of the few molecules in this category with approval as a medicine. The US FDA approved it on 21 June 2019 under the brand name Vyleesi. The indication is narrow and worth reading in full, because product descriptions sometimes stretch it.
The medicine is approved for premenopausal women with acquired, generalised hypoactive sexual desire disorder, HSDD for short, when it causes marked distress or interpersonal difficulty. The indication does not cover cases where low desire is due to another illness, to medication, or to problems in the relationship.
A detail that rarely reaches product descriptions: the prescribing information states plainly that the mechanism by which desire improves is unknown. What is known is that the molecule binds to melanocortin receptors in the central nervous system, not how that binding leads to the reported effect.
How large the effect was in the registration trials
Moderate, and the numbers say it better than an adjective. An increase in the desire score of 1.2 points or more was seen in about 25 per cent of people treated with bremelanotide, against about 17 per cent in the placebo group. The gap between those percentages is what the medicine added over placebo.
The approved product is injected subcutaneously into the abdomen or thigh from a ready-made autoinjector, at least 45 minutes before planned sexual activity. It is an as-needed medicine, not a daily one.
Why research material is not a medicine
A peptide sold as research material is not the medicine Vyleesi, even though it contains the same molecule. The approved medicine has a known dose, pharmaceutical quality control and a ready autoinjector with a measured portion. A vial of lyophilised powder has none of those three things, and the first two are exactly what you pay for at a pharmacy.
For the same reason we give no administration protocols here. For melanotan 2 there is nowhere to take them from, because the molecule has not been approved anywhere, and for bremelanotide the leaflet protocol applies to a medicine with a specific autoinjector, not to powder in a vial. This distinction is covered in more depth in the guide to the legal status of peptides.
What we stock and at what price
| Product | Contents | Price | Price per milligram |
|---|---|---|---|
| MT-2 (Melanotan II) by Genheal | 10 mg | 25 EUR | 2.50 EUR |
| MT-2 (Melanotan) by Bio-Peptide | 10 mg | 25 EUR | 2.50 EUR |
| PT-141 (Bremelanotide) by Genheal | 10 mg | 25 EUR | 2.50 EUR |
| PT-141 (Bremelanotide) by Bio-Peptide | 10 mg | 30 EUR | 3.00 EUR |
All four vials hold 10 mg of lyophilised powder, so the difference in price per milligram is at most 50 cents. Both compounds are in the libido and tanning peptides category, and storage conditions for the powder and the finished solution are in the guide to storing peptides.
Frequently asked questions
Is melanotan 2 approved anywhere?
No. It has no approval for any medical use in any country and is sold as research material for laboratory use.
Is melanotan 2 the same as melanotan I?
No. Melanotan I, or afamelanotide, is a medicine used in erythropoietic protoporphyria. Melanotan 2 is a different molecule with no approval.
Why is darkening of moles a problem?
Because it makes melanoma harder to detect. A change that darkens along with the rest of the skin is less noticeable when moles are checked.
Is PT-141 bought as research material the same as Vyleesi?
No. Vyleesi has a known dose, quality control and a ready autoinjector. A vial of lyophilised powder has none of these.
How effective was bremelanotide in trials?
An increase in the desire score of 1.2 points or more was seen in about 25 per cent of treated people against about 17 per cent on placebo.
This is information about products and the state of research, not medical advice. We sell both peptides as material for laboratory research, and whether their use is appropriate is for a doctor to judge.
Brands and prices are gathered on the melanotan II page.
Sources
- FDA approves new treatment for hypoactive sexual desire disorder in premenopausal women. Press release, US Food and Drug Administration (FDA), 21 June 2019. https://www.prnewswire.com/news-releases/fda-approves-new-treatment-for-hypoactive-sexual-desire-disorder-in-premenopausal-women-300872998.html
- VYLEESI (bremelanotide injection). FDA-approved prescribing information, NDA 210557, 2019. https://www.accessdata.fda.gov/drugsatfda_docs/label/2019/210557s000lbl.pdf
- Scenesse (afamelanotide). European public assessment report (EPAR), European Medicines Agency. https://www.ema.europa.eu/en/medicines/human/EPAR/scenesse
- Melanotan II tanning peptide products found to be inconsistently dosed. Therapeutic Goods Administration (TGA), Australia. https://www.tga.gov.au/safety/safety-monitoring-and-information/safety-alerts/melanotan-ii-tanning-peptide-products-found-be-inconsistently-dosed