PT-141

PT-141, known generically as Bremelanotide, is a short cyclic peptide that came out of the University of Arizona melanocortin programme in the late 1990s. It is a deliberate truncation and cyclisation of Melanotan-II, with the C-terminal amide swapped for a free acid. The chemistry change matters: it kept the receptor activity and dropped the skin-pigmentation behaviour that made MT-II noisy in pharmacological assays. The molecule that ends up in the vial is a seven-residue cyclic peptide with a molecular weight of about 1025 g/mol.

The receptor it actually hits

PT-141 is an agonist at the melanocortin receptors, with selectivity skewed toward MC3R and MC4R. The MC4R interaction is the one most of the published work circles around, because it sits in the central nervous system rather than peripheral vasculature. That mechanistic detail is the reason PT-141 keeps getting cited as the textbook example of a centrally acting agonist in a field otherwise dominated by vascular-targeted compounds. For in vitro receptor pharmacology and CNS-signalling assay work, that distinction is what makes it useful as a reference ligand.

The clinical lineage worth knowing

Palatin Technologies took Bremelanotide through full clinical development and, in 2019, the FDA approved it under the brand name Vyleesi for hypoactive sexual desire disorder in pre-menopausal women. That regulatory history matters for one reason only: it means the pharmacokinetics, receptor profile and metabolite picture have been mapped in detail in peer-reviewed and regulatory literature. For a laboratory referencing PT-141 in a comparative study, the published data set is unusually deep for a peptide of this size.

Vial contents and provenance

• Lyophilised PT-141 sealed under inert atmosphere in a tamper-evident glass vial
• Synthesised at a UK or EU contract peptide manufacturer we have audited
• Purity 98 percent or higher by reverse-phase HPLC, sequence confirmed by mass spectrometry
• Batch-specific Certificate of Analysis with chromatogram and MS trace, lot number on the label

We do not list PT-141 sourced from unverified Asian suppliers. The failure mode there is rarely a clean purity number low enough to spot at the bench. It is usually a sequence misidentification or counter-ion drift, both of which quietly skew receptor binding data. If a batch you receive does not match its CoA, the order is refunded. Same rule across the catalogue.

Getting it on your bench

Stock is held in the UK and posted from the UK in temperature-stable packaging. Roughly nine in ten UK orders arrive within 48 hours. Lyophilised PT-141 is stable at room temperature short term but should move to a freezer at minus 20 C on arrival for any meaningful storage window. Once reconstituted, refrigerate and use within a couple of weeks for assay work where peptide integrity has to be defensible.

If you need ten or more vials for a longer protocol, message support rather than adding to cart in a loop. Bulk pricing happens through a real conversation. Live chat during UK hours is staffed by humans, including the people who pack the orders, so questions about reconstitution buffer choice or how to read a particular CoA peak get a useful answer.

Sold strictly for in vitro laboratory research. Not for human or veterinary use. UK 18+.