We report net peptide content, not just purity — so the milligrams you dose aren't padded with water and counter-ion. RP-HPLC purity and ESI-MS identity, on a lot-numbered COA.
Net peptide content, not just purity — RP-HPLC + ESI-MS, lot-numbered COA.
Net peptide content on every lot's COA.
Reading a Peptide HPLC Trace — A 5-Minute Field Guide for Bench Scientists. Read our briefing →
Reading a peptide HPLC trace — a field guide. Read →
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Melanocortin-4 receptor agonist · approved for HSDD
Lyochem primary owner
This Lyochem page is the primary SEO owner for research labs, CROs, and method-development teams qualifying PT-141 (Bremelanotide) as a documented research-standard lot. The page should answer whether the buyer can review HPLC purity, identity confirmation, lot continuity, stability handling, and assay-fit documentation before ordering.
Overview
PT-141 (Bremelanotide, marketed as Vyleesi) is a synthetic cyclic heptapeptide built on the Melanotan II scaffold but tuned for preferential agonism at MC4R over the remaining melanocortin receptors. That MC4R bias is what underlies its central activity: downstream engagement of dopaminergic circuitry tied to sexual-arousal physiology, while largely sparing the pigmentation and cardiovascular responses associated with MC1R and MC3R signaling. It received FDA approval in 2019, under the Vyleesi name, for hypoactive sexual desire disorder in premenopausal women, administered as an on-demand subcutaneous injection. Lyochem supplies PT-141 (Bremelanotide) as a lyophilized reference standard at ≥99.0% HPLC. Cyclization via a lactam bridge, following the same architectural logic as the MT-II scaffold, demands careful synthesis, so characterization pairs RP-HPLC purity with ESI-MS confirming the mass of the ring-closed species; water content and counter-ion are documented on release. For any injectable research or compounding application, endotoxin (LAL) and microbial-limits testing are recommended additions. Being an approved medicine, clinical use should draw on the locally authorized finished product rather than bulk active; the bulk peptide here is intended solely for research and qualified compounding purposes.
Applications & buyer fit
Academic Laboratories
Universities, medical schools, and government research institutes qualifying a reference standard for a method-development or in vivo workflow.
Biotech R&D Groups
Preclinical biotech and pharmaceutical discovery teams sourcing characterized peptides for receptor-pharmacology, screening, and method-development campaigns.
Every release ships with its own batch-specific CoA — identity, purity, and the analytical scope agreed at quote stage, tied to the exact lot you receive.
Review a representative batch CoA before you order, so you can confirm the packet matches what your method or sponsor audit needs.
Supplied strictly as a research reagent to research institutions — not a finished dosage form and not for human administration. Buyer qualification runs at the inquiry stage.
Specifications
Documentation available on request
Regulatory note
In the US this compound is approved as a prescription drug (Vyleesi) for premenopausal HSDD, and across most major jurisdictions it remains heavily regulated. A compliance review is required before an order proceeds, and sales are limited to qualified buyers holding appropriate licensing in their jurisdiction.
Selected literature
Frequently asked questions
The disulfide-cyclized backbone changes both chromatographic and mass behavior, so it must be verified rather than assumed. RP-HPLC separates the intended cyclic form from any linear precursor or oligomeric by-product, which elute at different retention because ring closure alters conformation and hydrophobicity. ESI-MS confirms the intact mass; the cyclized species reads two mass units lighter than its reduced linear counterpart, so the observed value directly reports whether closure occurred. Because PT-141 shares the melanocortin heptapeptide scaffold with Melanotan II, we confirm the specific mass and retention for the supplied compound on the COA rather than relying on class similarity.
Family members built on the same cyclic heptapeptide template differ by only a few residues, so nominal name is not sufficient identity evidence. The practical discriminators are exact intact mass by ESI-MS and retention time under a fixed RP-HPLC method run alongside a known reference, since substitutions that shift receptor selectivity also shift mass and elution. Where two candidates are near-isobaric, LC-MS/MS fragmentation resolves them by sequence. We anchor each lot to its measured mass and chromatographic behavior on the certificate, giving a qualifying lab concrete analytical handles rather than a label to confirm the received material is the intended compound.
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