Bremelanotide Half-Life & Stability
Part of the full Bremelanotide guide - a synthetic cyclic heptapeptide; alpha-melanocyte-stimulating hormone reference compound, identity-verified with a COA on every vial.
In brief
For PT-141, stability and pharmacokinetic behavior are best understood at two levels: the structure-driven degradation resistance that is specifically documented for this molecule, and the general peptide-class principles that govern handling where compound-specific numbers are not provided in the entry. The provided data does not state a defined half-life value, so no such figure is asserted here. What the entry does establish is that bremelanotide's cyclic architecture, the Asp-Lys lactam bridge together with the D-Phe substitution and N-acetyl-Nle cap, confers resistance to enzymatic degradation relative to linear melanocortin peptides, a structure-activity feature studied in receptor-pharmacology and conformational work. The entry also references pharmacokinetic study of intranasal PT-141 as part of its citation trail. The sections below separate what is supported specifically by the molecule's structure from the broader storage and stability conventions that apply generally to research peptides, keeping the distinction explicit throughout.
The detail
A closer look
01
Structure-driven degradation resistance
The clearest stability statement in the data is structural rather than numerical. PT-141's backbone is cyclized through an Asp-Lys lactam bridge and capped at the N-terminus with N-acetyl-Nle, and it incorporates a D-Phe residue in place of the native L-phenylalanine. Each of these features works against enzymatic attack: cyclization removes the free termini and flexible conformations that proteases recognize, the acetyl cap blocks aminopeptidase action at the N-terminus, and the D-amino acid substitution presents a stereochemistry that mammalian peptidases cleave poorly. The entry states explicitly that these modifications confer resistance to enzymatic degradation relative to linear melanocortins, and that this is a structure-activity feature examined in the receptor-pharmacology and enzymatic-stability literature. This degradation resistance is the molecule-specific basis for expecting greater handling durability than an unmodified linear alpha-MSH fragment would show.
02
General peptide-class storage and stability principles
Where the entry provides no compound-specific kinetic constants, only general peptide-class principles apply, and they are flagged as general here. Lyophilized synthetic peptides are typically most stable as the dry powder held cold and desiccated, while reconstituted aqueous stocks are more labile and are conventionally kept refrigerated for near-term use with frozen aliquots for longer storage. Repeated freeze-thaw cycling, prolonged warmth, and light exposure are the usual degradation accelerants that handling practice aims to limit. The pharmacokinetic study of intranasal PT-141 referenced in the citation trail (Diamond et al., 2004) documents that the molecule's in-vivo pharmacokinetics have been characterized, but the entry supplies no half-life number to report. Accordingly, any expectation of in-solution longevity rests on the general conventions above plus the molecule-specific degradation resistance, not on a stated quantitative half-life.
The fine print: products are sold for laboratory research use only and are not for human or animal consumption. Bodily introduction into humans or animals is strictly prohibited by law. Bremelanotide is not a drug and is not intended to diagnose, treat, cure, or prevent any disease. These statements have not been evaluated by the FDA.