PT-141 (Bremelanotide) Testing
MW: 1025.18 g/molHalf-life: ~2 hoursStatus: FDA-approved
Melanocortin-receptor agonist derived from Melanotan II. FDA-approved as Vyleesi.
Mechanism of action
Bremelanotide is a cyclic melanocortin receptor agonist (primarily MC4R and MC1R) derived from Melanotan II. Centrally mediated effects on sexual response — distinct from PDE5 inhibitors which act vascularly.
Sequence & structure
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH
Cyclic via a lactam bridge between Asp and Lys side chains. Cyclization confirmation is essential — linear precursor is the most common impurity.
Research areas
- ●Hypoactive sexual desire disorder (FDA-approved as Vyleesi)
- ●Erectile function research
- ●Melanocortin-pathway studies
What we test on PT-141 (Bremelanotide)
RP-HPLC purity, intact-mass LC-MS (to confirm cyclization), MS/MS sequence with stereochemistry confirmation, endotoxin.
Standard Sexual Health Panel
- ✓RP-HPLC purity
- ✓LC-MS (cyclization confirmation)
- ✓Disulfide bond mapping
Common impurities & failure modes
- Linear (uncyclized) precursor
+18 Da vs. main peak; primary identity QC parameter for any cyclic peptide.
- Racemized D-Phe → L-Phe
Eliminates receptor selectivity; chiral analysis required.
- Trp oxidation
+16 / +32 Da peaks.
- Loss of N-terminal acetyl
−42 Da shift.
Regulatory status
FDA-approved (Vyleesi 2019).