Bremelanotide Reconstitution Guide
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
Laboratory reconstitution of PT-141 follows the standard handling pathway for a lyophilized research peptide intended for in-vitro receptor and signaling assays. Like other synthetic peptides supplied as a freeze-dried powder, bremelanotide is dissolved before use to yield a defined-concentration stock solution suitable for serial dilution into binding or cAMP-accumulation assays. The relevant constants are the molecule's molecular weight of 1025.2 g/mol and its known mass per vial, which together govern the concentration math. Bacteriostatic water is the conventional reconstitution diluent because the benzyl alcohol it contains limits microbial growth across repeated draws from a multi-use stock, supporting stability during a working assay series. The guidance below describes preparation, concentration calculation, and storage strictly for laboratory in-vitro handling. It is not a human dosing protocol and contains no administration instructions; the figures exist only to produce a known molar concentration for bench pharmacology with a melanocortin reference ligand.
The detail
A closer look
01
Reconstitution principle and concentration math
Reconstitution converts a weighed mass of lyophilized peptide into a stock of known molar concentration by dissolving it in a measured diluent volume. The arithmetic rests on two values: the peptide mass in the vial and the molecular weight, 1025.2 g/mol. Mass concentration is simply peptide mass divided by diluent volume; for example, 5 mg dissolved in 2 mL gives 2.5 mg/mL. Converting to molarity uses moles equals grams divided by molecular weight, so 2.5 mg/mL of a 1025.2 g/mol peptide is roughly 2.44 mM, a convenient stock from which nanomolar to micromolar working dilutions are prepared for binding and cAMP assays. Adjusting the diluent volume up or down shifts the resulting concentration proportionally, letting researchers target whatever stock molarity their assay layout requires while keeping the molecular weight as the fixed conversion constant.
02
Stability and storage handling
As a constrained cyclic peptide, PT-141 carries structural features, the Asp-Lys lactam bridge and the D-Phe substitution, that confer resistance to enzymatic degradation relative to linear melanocortins, which is favorable for stability during handling. General research-peptide practice still applies: the lyophilized powder is the most stable form and is kept cold and desiccated until reconstitution, while reconstituted stock is held refrigerated for short-term use and aliquoted for longer-term frozen storage to avoid repeated freeze-thaw cycles. Bacteriostatic water as the diluent supports a multi-draw working stock. Stocks should be protected from prolonged warmth and light, and aliquoting at the time of reconstitution preserves assay-to-assay consistency by limiting how often any single fraction is thawed and refrozen across an experimental series.
Step by step
How Bremelanotide is reconstituted
A bench reference for handling and preparation in an in-vitro research setting. Not a personal dosing protocol.
- 1
Allow the sealed vial of lyophilized PT-141 and the bacteriostatic water to equilibrate to room temperature before opening.
- 2
Calculate the diluent volume needed for your target stock concentration using the molecular weight of 1025.2 g/mol and the known peptide mass per vial (e.g., 2 mL into 5 mg yields 2.5 mg/mL, ~2.44 mM).
- 3
Draw the calculated volume of bacteriostatic water and introduce it slowly down the inner vial wall rather than directly onto the peptide cake.
- 4
Let the vial stand and swirl gently until fully dissolved; do not shake or vortex vigorously, which can stress the peptide.
- 5
Visually confirm a clear, particle-free solution before use in any assay.
- 6
Label the stock with concentration and date; refrigerate for short-term in-vitro use and prepare frozen aliquots to avoid repeated freeze-thaw cycles.
- 7
Dilute the stock into assay buffer to the required nanomolar-to-micromolar working concentrations immediately before each binding or cAMP-accumulation experiment.
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.