PT-141

Scientific identity. PT-141 (Bremelanotide) is a cyclic heptapeptide sharing the core cyclic structure of Melanotan 2 — the Asp–Lys lactam bridge creating a constrained ring — with the key structural distinction that the C-terminal amide (NH₂) of Melanotan 2 is replaced by a free hydroxyl (OH) group at the C-terminus. This modification alters the compound's melanocortin receptor activity profile: PT-141 retains potent MC3R and MC4R agonist activity studied in central nervous system melanocortin research but has reduced MC1R-mediated melanogenic activity relative to Melanotan 2 in experimental systems. The sequence is Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-OH.

Peptide class. Synthetic cyclic heptapeptide; melanocortin receptor agonist; α-MSH core-sequence analogue; POMC-derived peptide analogue; MC3R/MC4R selective agonist.

Primary receptor targets. MC3R and MC4R — class A GPCRs expressed in hypothalamic and limbic CNS regions, coupled to Gαs-mediated cAMP signaling. MC4R in the CNS is studied in the context of sexual behavior neuroscience models, appetite regulation, and energy homeostasis research. MC3R is studied in relation to energy homeostasis and feeding behavior models.

Research areas. Melanocortin receptor pharmacology, MC3R and MC4R CNS signaling research, sexual behavior neuroscience models, appetite and energy homeostasis research, hypothalamic melanocortin pathway biology, comparative melanocortin peptide pharmacology.

Product quantity. 10mg per vial.

Physical form. Supplied as a lyophilised solid in a sealed research vial.

Purity. Greater than 99%, confirmed by HPLC and LC-MS analysis at the batch level.

Analytical documentation. A batch-specific Certificate of Analysis is available on the Longevia Research website, covering compound identity, purity, and lot traceability.

Research-use classification. For laboratory research use only. Not for human or veterinary use, clinical diagnostics, or any in-vivo application in humans outside of regulated research settings.

Melanocortin Receptor Pharmacology and PT-141 Selectivity

PT-141's defining pharmacological feature relative to Melanotan 2 is its altered melanocortin receptor activity profile attributable to the C-terminal hydroxyl modification. Published receptor pharmacology has characterised PT-141 as a potent MC3R and MC4R agonist with reduced MC1R melanogenic activity relative to Melanotan 2, making it a more selective research tool for investigating central melanocortin receptor pharmacology independently of peripheral melanogenic effects. MC3R and MC4R are class A GPCRs coupled to Gαs, activating cAMP-dependent signaling in hypothalamic and limbic neurons. These receptor pharmacology findings are from defined cell-based assay systems.

MC4R and Central Nervous System Research

MC4R is expressed in multiple hypothalamic nuclei — including the paraventricular nucleus and ventromedial hypothalamus — and in limbic regions including the hippocampus and amygdala. Research has examined MC4R in relation to energy homeostasis, feeding behavior, and sexual behavior neuroscience models in animal experimental systems. PT-141's potent MC4R agonist activity has made it a research tool for investigating MC4R-mediated CNS signaling in these contexts. These are animal model findings in defined experimental systems.

Distinction from Melanotan 2

PT-141 and Melanotan 2 are structurally near-identical but pharmacologically distinct due to the single C-terminal modification. In research contexts requiring separation of central melanocortin receptor effects (MC3R/MC4R) from peripheral melanogenic effects (MC1R), PT-141 offers a more selective tool than Melanotan 2. Researchers designing experiments to investigate central melanocortin signaling while minimising melanogenic pathway engagement should account for this distinction when selecting between the two compounds.

Human Clinical Research and Regulatory Status

PT-141 (Bremelanotide) was investigated in human clinical trials — including trials examining sexual function endpoints in premenopausal women — leading to FDA approval of Vyleesi (bremelanotide subcutaneous injection) in 2019 for hypoactive sexual desire disorder (HSDD) in premenopausal women. This approval concerns a specific pharmaceutical subcutaneous injection formulation under defined clinical and regulatory conditions and does not establish the safety, efficacy, pharmacokinetic equivalence, or bioavailability of the Longevia Research research vial.

Reliable research begins with accurately characterised material. For PT-141, the defining quality consideration is distinguishing it from Melanotan 2 — compounds that differ by only 1 g/mol and share the same cyclic scaffold. LC-MS identity confirmation is essential to verify the C-terminal hydroxyl form (PT-141, CAS 189691-06-3) rather than the C-terminal amide form (Melanotan 2, CAS 121062-08-6), as the two have substantially different melanocortin receptor activity profiles that would directly confound selectivity research.

Purity assessment. Each production lot is characterised to greater than 99% purity by high-performance liquid chromatography (HPLC). Chromatographic purity data is reported on the batch Certificate of Analysis.

Identity confirmation. Peptide identity, cyclic lactam bridge integrity, D-Phe configuration, and C-terminal hydroxyl group are confirmed by mass spectrometry (LC-MS), providing molecular-weight verification consistent with PT-141 (1025.17 g/mol free peptide) rather than Melanotan 2 (1024.18 g/mol). HPLC and LC-MS data together confirm that the material supplied corresponds to the labelled compound at the labelled purity.

Batch traceability and Certificate of Analysis. Every vial of PT-141 10mg is traceable to a specific production lot. A batch-specific Certificate of Analysis is accessible directly on the Longevia Research website, covering purity, identity, and lot information. Researchers are particularly encouraged to verify compound identity — including CAS number and molecular weight — from the batch COA before use, given the close structural similarity to Melanotan 2.

Handling. This material should be handled by qualified personnel using appropriate laboratory technique and personal protective equipment, consistent with institutional protocols for research-grade cyclic synthetic peptides.

Longevia Research supplies PT-141 10mg for laboratory and in-vitro research use only. The product is intended for use by qualified researchers and trained laboratory personnel in appropriate controlled research environments.

PT-141 is a synthetic research peptide supplied strictly as a research tool. It is not a drug, not a dietary supplement, not a food or food ingredient, and not a cosmetic. While PT-141 (Bremelanotide) is the active pharmaceutical ingredient in FDA-approved Vyleesi (subcutaneous injection for HSDD in premenopausal women, approved 2019), that approval concerns a regulated pharmaceutical formulation under defined clinical and manufacturing conditions entirely distinct from the Longevia Research research vial, which is not a pharmaceutical product and has not been evaluated by any regulatory authority for safety or efficacy in this formulation.

Longevia provides no dosing instructions, administration guidance, treatment protocols, or reconstitution recommendations for this compound. The scientific literature summarised on this product page describes experimental observations in defined cell-based, animal, and regulated human clinical research systems. Those findings are not medical claims and should not be interpreted as evidence of human efficacy, human safety, or fitness for any clinical application from this product.

The purchaser assumes full responsibility for lawful acquisition, handling, storage, use, and disposal of this material, and for compliance with all applicable local, state, federal, and institutional regulations. By purchasing this product, the buyer confirms that it will be used solely for legitimate laboratory research purposes by qualified personnel, and that its acquisition and intended use comply with applicable laws in the buyer's jurisdiction.