PT-141 (Bremelanotide)
PT-141 is a lab-made peptide: a short chain of seven amino acids, closed into a ring, modeled on a natural hormone called alpha-MSH.
Where it came from
PT-141's story starts in Tucson. In the late 1980s, chemist Victor Hruby and physiologist Mac Hadley at the University of Arizona set out to build a sturdier version of alpha-MSH, a natural hormone 13 amino acids long that breaks down within minutes. In 1989 their group (Fahad Al-Obeidi, Hruby, Hadley and B. Montgomery Pettitt) published a new family of ring-shaped versions of alpha-MSH in the Journal of the American Chemical Society. Closing the peptide into a ring locked its shape and made it far more stable.
The university licensed one of those ring-shaped versions to Palatin Technologies, a company in Cranbury, New Jersey. Around 2000, Palatin set it aside and turned to a close relative: the same seven-amino-acid ring with one small change at the end of the chain. Palatin made, patented and developed that molecule under the code name PT-141. Its official generic name is bremelanotide.
Worth knowing
- PT-141 is a short chain of seven amino acids, the building blocks of every peptide. Six of the seven are closed into a ring, like a bracelet with a short tail. Closing the ring holds the molecule in one shape, which makes it much more stable than the natural hormone it was modeled on.
- Three of its building blocks are lab-made versions not found in natural proteins: a small chemical cap on one end, a swapped-in piece that reacts less easily with oxygen, and a mirror-image form of a common amino acid. These small edits help the molecule stay intact longer than the natural hormone.
- Its only difference from the Arizona parent compound is one tiny group of atoms at the very end of the chain. That changes its weight by about 1 unit out of roughly 1,025, which is why the identity check on a lab report has to be read closely.
- The molecule has a courtroom history. Competitive Technologies, the firm that handled the Arizona license, sued Palatin over who owned bremelanotide. The case settled in January 2008: Palatin kept bremelanotide and paid $800,000.
- In December 2023, Palatin sold its rights in the compound to Cosette Pharmaceuticals in a deal worth up to $171 million.
At a glance
| Detail | Value |
|---|---|
| Chain length | 7 amino acids |
| Chemical formula | C50H68N14O10 |
| Weight of one molecule | 1025.2 g/mol |
| Form | Freeze-dried powder |
| Storage | Sealed in a freezer at -20 °C, away from light |
Weight is shown in grams per mole (g/mol), the standard unit chemists use. It's the number a lab checks a sample against to confirm it's the right compound.
Lab reports
Every batch (called a lot) of PT-141 (Bremelanotide) is tested by an independent lab. The report shows the lab, the test date, the lot number, how pure the sample is and how much is in the vial. Find them on the Certificates of Analysis page. New to lab reports? Start with How to read a peptide lab report.
The weight above is for the compound on its own. A report may show a slightly higher figure, because the powder also carries a little salt left from manufacturing. Peptide salt forms explains why.
Storage
Keep the vial sealed in a freezer at -20 °C, away from light, and let it warm to room temperature before opening so moisture doesn't get in. More in Storing lyophilized (freeze-dried) peptides in the lab and the Research handling guidelines.
For research use only. Not for human or veterinary use.