PT-141 vs Vyleesi: Active Ingredient, Formulation & FDA Approval

The distinction that matters

PT-141 and bremelanotide may be named as the same development active peptide. Vyleesi is something else: an approved pharmaceutical product, with a formulation, an application file, and an indication. Active-ingredient evidence is not pharmaceutical-product equivalence.

Five categories, not one

PT-141 as a development name

Early literature and several registry records use PT-141 for the same peptide later named bremelanotide. That name relationship is useful. It does not turn a commercial vial into the approved file.

Bremelanotide as the active moiety

FDA describes bremelanotide as a synthetic cyclic heptapeptide. The active-moiety UNII is 6Y24O4F92S. The free-base molecular weight on the current label is approximately 1025.2.^1,3

Bremelanotide acetate

The product marketed today is a bremelanotide acetate formulation. The acetate UNII is PV2WI7495P. A mass consistent with the moiety does not, by itself, demonstrate that salt or that formulation.^1,4

Vyleesi as a finished product

FDA approved the drug product Vyleesi, containing bremelanotide, for a specific indication on June 21, 2019, NDA 210557. That approval covers the application, the formulation, the manufacturing controls, the route, and the product specifications. It does not automatically extend to a third-party vial labeled PT-141.^2,1

Peptra research material

Peptra sells a research material labeled PT-141. The certificate of analysis for the 10 mg presentation names the sample PT-141 10mg, reports HPLC-UV and intact-mass identification, and prints the cyclic bremelanotide sequence. It does not establish acetate. It does not establish equivalence to Vyleesi. It does not establish finished-product sterility or bioequivalence.

If the observed mass is consistent with the bremelanotide moiety, that is exactly what can be said: mass consistent with the moiety. A finished drug is not inferred. See the commercial PT-141 page

The table’s final row is not a detail. It is the point of the page. Even if the certificate mass is consistent with the active moiety, equivalence to Vyleesi remains NO. Equivalence would require, at minimum, a documented matching salt form, the same formulation, the same manufacturing controls, and evidence Peptra does not have. None of that appears in an HPLC-UV result or an intact mass.

Sharing a name is not enough either. PT-141 and bremelanotide may name the same development peptide. Vyleesi names a product. A product has an NDA, a date, an indication, and a list of what is not indicated. A vial has a lot, a certificate, and a research-use notice. Moving from the first to the second by analogy is the error this comparison exists to prevent.^2,1

Acetate illustrates the same problem at molecular scale. The marketed product uses bremelanotide acetate. That salt’s UNII is not the active-moiety UNII. If Peptra’s certificate does not establish acetate, the vial is not written as “bremelanotide acetate.” It is written as what it has: a commercial name, a printed sequence, and a reported mass.^3,4

Route and delivery belong to the product, not to the peptide. Vyleesi is described as an injectable solution in an autoinjector. Peptra material is a lyophilized powder. That difference is not cosmetic. It is part of what approval covers and what a third-party vial does not inherit. Active-ingredient evidence is not pharmaceutical-product equivalence.¹

That is why the forbidden sentences on this page are literal: not “same as Vyleesi,” not “generic Vyleesi,” not “FDA-approved PT-141,” not “FDA-approved peptide,” not “pharmaceutical grade equivalent.” Each one collapses a category the table keeps apart. The expected count of those claims, on the product and in this comparison, is zero.

What not to claim

• Not: “same as Vyleesi.”
• Not: “generic Vyleesi.”
• Not: “FDA-approved PT-141.”
• Not: “FDA-approved peptide.”
• Not: “pharmaceutical grade equivalent.”

A certificate can be honest and still be insufficient to cross that line. Reporting PT-141 10mg, 99.71% by HPLC-UV, and 1025.19 Da by LC-MS is analytical documentation. Turning those numbers into “same as Vyleesi” is a pharmaceutical-product claim. This page accepts the first and rejects the second.

The same logic applies to the NDA. June 21, 2019 approves an application. It approves a product, a formulation, and an indication. It does not approve a catalog name. Someone who reads “bremelanotide” on a vial and “bremelanotide” on a Vyleesi label has not demonstrated equivalence. They have demonstrated a name overlap that this comparison refuses to treat as product identity.²

Next reading

• Read the approval and its limits
• Return to the peptide definition
• Back to the research hub