This page compares what is documented about Melanotan II and PT-141, rather than ranking them by effect. What each molecule is, the sizes and prices actually carried, what the certificate covers, and how the two differ on the bench. Everything here is research-use-only material and we do not publish outcome, dosing or administration content for any compound in the catalogue.
What is Melanotan II and what is PT-141?
Melanotan II. Melanotan II is the original synthetic melanocortin analogue from the University of Arizona programme — still cited as the reference non-selective agonist in receptor studies.
PT-141. PT-141 (bremelanotide's research form) is a cyclic melanocortin-receptor agonist — the standard probe compound for MC3R/MC4R work in receptor-pharmacology studies.
How do Melanotan II and PT-141 compare on price and size?
| Melanotan II | PT-141 | |
|---|---|---|
| Sizes carried | 10 mg | 10 mg |
| From | $35.00 | $40.00 |
| Best price per unit | $3.50 / mg | $4.00 / mg |
| Availability | Backordered — waitlist | Backordered — waitlist |
| Certificate | Lot certificate on the product page | Lot certificate on the product page |
| Molecular formula | C50H69N15O9 | C50H68N14O10 |
| Molar mass | 1,024.2 g/mol | 1,025.2 g/mol |
| Source | PubChem CID 92432 | PubChem CID 9941379 |
| Research area | melanocortin research | melanocortin-receptor research |
At their best sizes Melanotan II works out at $3.50 per mg against $4.00 for PT-141 — 14% more for the mg. Vial prices start at $35.00 and $40.00 respectively, which is the number most people compare and the one that says least, because the two are not sold in the same sizes. Full sizes, tier pricing and the lot certificate sit on the Melanotan II page and the PT-141 page.
What is each one studied for?
What the published literature investigates, which is a different question from what either will do, and the only one of the two a supplier can answer.
Melanotan II is studied in melanocortin research. Non-selective melanocortin agonists remain standard tools in receptor-pharmacology work, with Melanotan II the most-cited of them.
PT-141 is studied in melanocortin-receptor research. Melanocortin-receptor pharmacology keeps a steady publication rate, with PT-141 the most-used agonist probe in that literature.
Studied in the same area does not make two compounds interchangeable, and the research library holds the per-compound documentation.
PT-141 vs Melanotan 2: how they differ on the bench
PT-141. Cyclic peptides like PT-141 resist degradation better than linear chains, which is why its storage window is one of the more forgiving in the catalog.
Melanotan II. MT-II's lactam bridge is what our identity work verifies; the linear precursor is a different compound that a bare mass check can miss.
On naming, because the two are written several ways and the difference is not always obvious: Melanotan II is also written melanotan 2. They refer to the same materials described here, and the certificate for a lot uses the name on this page. The comparison itself is usually typed Melanotan 2 vs PT-141.
What actually differs between PT-141 and Melanotan II
The two are within a few percent of each other on molar mass — Melanotan II at 1,024.2 g/mol and PT-141 at 1,025.2 g/mol — so a milligram of one is close to the same number of molecules as a milligram of the other. That is unusual, and it is the only case where comparing the two by mass alone is nearly the same as comparing them by amount of substance.
Identity is the other analytical axis, and it is settled per lot rather than per compound. Melanotan II. Catalogued as Melanotan II, and the certificate's identity test resolves to that. PT-141. Catalogued as Bremelanotide, and the certificate's identity test resolves to that.
Both are released against a certificate reporting identity, purity by the stated method and net peptide content, readable before anything is bought.
Which is better, PT-141 or Melanotan 2?
Neither PT-141 nor Melanotan 2 is ranked against the other here, and the refusal is deliberate. Better, safer and stronger are questions about effects in a living system, and we sell neither compound for use in one — why none of these pages ranks two compounds sets out the reasoning in full.
What it does instead, for these two:
- Melanotan II is the cheaper of the two per mg, at $3.50 against $4.00.
- Their molar masses are within a few percent, so a milligram of either is close to the same amount of substance.
- Both are carried in 1 size, and each lot carries its own certificate.
Every one of those is checkable before you buy.
Common questions
What is the difference between PT-141 and Melanotan II?
Different molecules before anything else: PT-141 is C50H68N14O10 and Melanotan II is C50H69N15O9. PT-141 (bremelanotide's research form) is a cyclic melanocortin-receptor agonist — the standard probe compound for MC3R/MC4R work in receptor-pharmacology studies. Melanotan II is the original synthetic melanocortin analogue from the University of Arizona programme — still cited as the reference non-selective agonist in receptor studies.
Which one should I choose?
Melanotan II is carried in 10 mg and PT-141 in 10 mg, each lot with its own certificate. Which of those suits the work is yours to decide; everything here is research-use-only rather than guidance for use in a human or an animal.
Do both Melanotan II and PT-141 come with a certificate of analysis?
Neither is in stock at the moment, so in each case the certificate is the one attached to the lot that arrives. A certificate belongs to a lot, not to a product. It is linked from the product page, and reports identity, purity by the stated method, and net peptide content for the material actually in that lot.
Which is cheaper, PT-141 or Melanotan II?
Per mg, Melanotan II at $3.50 against $4.00, taking each one's best size. By vial they start at $35.00 for Melanotan II and $40.00 for PT-141, which is the comparison most people make and the one that says least, because the two are not sold in the same sizes.
Is a milligram of Melanotan II the same as a milligram of PT-141?
By mass yes, and unusually so by amount of substance too: Melanotan II is 1,024.2 g/mol and PT-141 is 1,025.2 g/mol, within a few percent, so a milligram of either is close to the same number of molecules. That is rarely true of two different peptides and it is worth checking rather than assuming.
FOR LABORATORY AND IN-VITRO RESEARCH USE ONLY. NOT FOR HUMAN OR ANIMAL CONSUMPTION. NOT FOR PERSONAL, MEDICAL, DIAGNOSTIC, THERAPEUTIC, OR RECREATIONAL USE.