PT-141 (Bremelanotide): Reference Overview and Reconstitution Notes

PT-141 (Bremelanotide)

What it is

PT-141, also called bremelanotide, is a synthetic cyclic heptapeptide that acts as a melanocortin receptor agonist, with activity at the MC3R and MC4R receptors. It is structurally related to the melanocyte-stimulating hormone family and is derived from an earlier melanocortin compound.

Research context and categorization

PT-141 is generally categorized as a reproductive and sexual-health compound, and more broadly within the melanocortin receptor agonist family. It is most commonly discussed in relation to central pathways for sexual arousal and desire, because its receptor activity is centered in the brain rather than the vascular system. This central mechanism is different from that of vasodilator-based approaches, and it is the basis for its one approved use. Beyond that approved indication, PT-141 is sometimes discussed in relation to broader questions of arousal and libido across different populations, but those wider uses remain investigational and are not confirmed or approved outcomes.

Status

  • Regulatory status: FDA-approved for a specific indication. Bremelanotide is approved under the brand name Vyleesi for acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. Any use outside that specific indication is off-label or investigational.
  • Sport status: Not specifically listed on the WADA Prohibited List. As of the current List, bremelanotide is not named under any prohibited class. Because it is an FDA-approved substance rather than a wholly unapproved one, it does not fall under the S0 unapproved-substances category by default. Status can change with WADA's annual review, so competitive athletes should verify the current List directly.

Reconstitution notes (general)

PT-141 is supplied as a lyophilized (freeze-dried) powder that is reconstituted with bacteriostatic water before laboratory use. Concentration equals the milligrams of peptide in the vial divided by the millilitres of bacteriostatic water added. For example, a 10 mg vial reconstituted with 2 mL of bacteriostatic water gives a concentration of 5 mg/mL. To work out a target concentration for a given vial and water volume, see the calculator at our reconstitution and blend calculators.

Dilution and handling notes (compound-specific)

PT-141 research vials are most often supplied in 5 mg or 10 mg sizes. A 10 mg vial is commonly brought up in roughly 1 mL to 3 mL of bacteriostatic water, with 2 mL being a frequent choice because it yields a clean 5 mg/mL figure that is easy to measure on a standard insulin syringe. Larger water volumes lower the concentration and make small measured amounts easier to read, while smaller volumes concentrate the solution. The amount of water is chosen mainly to hit a convenient concentration rather than for solubility reasons.

PT-141 is one of the more cooperative peptides to reconstitute. As a small, water-soluble heptapeptide it generally dissolves readily and quickly into a clear, colourless solution, and it does not tend to gel, clump, or resist going into solution the way some larger or more hydrophobic peptides can. The practical technique still matters... let the vial reach room temperature, direct the bacteriostatic water slowly down the inner glass wall of the vial rather than spraying it straight onto the powder cake, then swirl gently or invert rather than shaking or vortexing, since aggressive agitation can foam the solution and promote aggregation, which is the main handling quirk to watch for. If the finished solution turns cloudy, develops colour, or shows particulate floaters, that points to aggregation, degradation, or contamination, and clarity cannot be restored by further dilution or filtering, so the vial should be discarded rather than salvaged. A nasal-spray research format also exists for this compound, which is a ready liquid preparation and does not involve the powder reconstitution step described above.

Handling and storage

  • Refrigerate at 2 to 8 degrees Celsius.
  • Keep out of light, before and after reconstitution.
  • Wipe the rubber stopper with an alcohol swab before each puncture.
  • Label the vial with the mix date so age can be tracked.
  • Observe the general roughly 4-week refrigerated window for the reconstituted solution.
  • Discard anything cloudy, discoloured, or containing floaters.

Related reading

Tools and supplies

For laboratory and research reference only. Educational content, not medical, dosing, injection, or therapeutic guidance, and not intended for human or animal use. Any research uses described are investigational and not confirmed or approved benefits. Confirm anything involving health with a licensed professional. References linked above.