Where to buy PT-141 Peptide: sizes, price per mg and how to verify the lot

What "pt-141 peptide" names, and what it does not

PT-141 is the development code for bremelanotide: a seven-residue synthetic peptide, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, in which the aspartate and lysine side chains are joined into a lactam ring and the C-terminus is a free acid. Formula C50H68N14O10, average mass 1,025.2 Da, PubChem CID 9941379. Palatin Technologies developed it, and the papers cited at the foot of this page are from that programme. Listings write PT-141, PT141, PT 141 and bremelanotide; one molecule. It is one dalton heavier than Melanotan II, from which it was derived, and that single dalton is the whole difference between two products.

An approved medicine, Vyleesi, contains bremelanotide and was approved by the FDA in 2019; the research vial is not that product. Vyleesi is manufactured under an approval to a specification and released against it. A research vial of PT-141 is a synthetic peptide with the same sequence sold as laboratory material and standing on its lot certificate. Listing it is not an approval, an equivalence or a safety claim, and this page describes the material, not any use in a person.

The chemistry a buyer can hold a seller to is the ring and the terminus. The lactam bridge is formed in synthesis and a lot where it failed is 18 Da heavier (the uncyclised precursor still carries its water); the C-terminal acid is what distinguishes PT-141 from Melanotan II's amide, one dalton lighter. A certificate that prints the observed mass to the dalton answers both questions; a rounded 1,025 answers neither, and a listing with no mass at all has not asked them.

The reference point for identity is public. PubChem lists Bremelanotide as CID 9941379 with molecular formula C50H68N14O10, an average molecular weight of 1025.2 Da and a monoisotopic mass of 1024.524 Da. Those are the numbers a mass spectrometer is checked against, and the number a certificate must print beside the observed mass.

In plain terms: A man-made ring-shaped peptide seven building blocks long that works on melanocortin receptors, also published as bremelanotide. What is sold here is a research chemical and not a drug product. Listing it is not an approval, an equivalence or a safety claim, and this record does not describe use in a person.

PT-141 for sale: sizes and price per mg

LabFirst lists PT-141 in one size (10mg) from $40, priced per vial with the per-mg figure beside it so sizes can be compared without arithmetic. It is sold in one size, 10mg, at $4 per mg.

The volume tiers are per size, not per basket: ten vials of one size take 10% off that line and twenty take 15%, and mixed sizes do not combine. Shipping is a flat $15 on orders under $200 and free from $200, within the United States only, with same-day dispatch on orders placed before 12 PM Pacific on a business day. The cost per mg tool runs the same comparison across any two listings, ours or anyone else's.

A cyclic heptapeptide with a norleucine, a D-phenylalanine and a lactam closure is a moderately expensive synthesis, and PT-141 is priced in the middle of the catalogue per milligram; LabFirst lists one 10 mg vial, and a laboratory qualifying a lot reads the mass to the dalton and the tryptophan peaks on its certificate before buying more. The volume tiers apply to that one size.

The price signal is the neighbour. Melanotan II is cheaper to make, one dalton lighter, and sold under the PT-141 name by sellers who do not distinguish them or hope the buyer will not; a PT-141 listing priced like Melanotan II should be read with the certificate's decimal place in view. "Same as Vyleesi" at any price is a different error, since the approved product's evidence does not transfer to a research vial. The only discounts on this page are the volume tiers, and the lot on the vial is whatever the certificate index says on the day.

The certificate a PT-141 lot must carry

Three tests answer three different questions, and a certificate of analysis for PT-141 is only complete when it carries all three for the exact lot on the vial. Identity is settled by mass spectrometry, and the number to look for on a PT-141 certificate is 1024.524 Da monoisotopic (or 1025.2 Da average, if the laboratory reports the deconvoluted average mass). The observed mass should sit within the instrument's stated tolerance of that figure, and the certificate should print both the theoretical and the observed value, not just a tick.

Purity is a separate question, answered by HPLC: how much of what came off the column was the compound. The figure is only interpretable with its method beside it (column, gradient, detection wavelength) and a date, which is what ICH Q2(R2) means when it asks that an analytical procedure be shown fit for its purpose. A percentage with no method and no date is a number somebody typed, and a certificate that carries every test but for a different lot number than the vial is the most common failure of all and the easiest to catch. Net content is the third test and the one most often missing: the milligrams of PT-141 actually in the vial, measured, against the size printed on the label.

Identity is the observed mass against 1,024.524 Da monoisotopic (1,025.2 Da average), seen in electrospray as m/z 1,025.5 for the singly charged ion and 513.3 for the doubly charged, printed to at least one decimal beside the theoretical value. One dalton low, 1,023.5, is Melanotan II, the amide, a different compound sold under a different name and sometimes under this one; 18 Da high is the uncyclised linear precursor, which some factories fail to close. Peaks at +16 and +32 Da are oxidised tryptophan. A certificate rounded to the nearest dalton cannot tell PT-141 from Melanotan II at all.

Purity by HPLC should show the chromatogram with its column, gradient and wavelength; the tryptophan gives a strong 280 nm signal that confirms the main peak is the tryptophan-containing molecule, and the linear precursor and the oxidised forms elute at different times on a good method. Net content is the third line: PT-141 is supplied as the acetate or trifluoroacetate, and with an arginine it carries counter-ion, so quantitative HPLC against a standard or amino acid analysis is what says how many of the labelled milligrams are peptide. The salt belongs beside that figure.

Where to buy PT-141: five checks before you order from anyone

Every seller of pt-141 peptide says "third-party tested". The phrase costs nothing. These five checks take about four minutes per listing and separate a tested lot from a tested-sounding one.

1. The lot on the vial is the lot on the certificate. Read the printed lot number, then open the certificate and match it. A certificate for "PT-141" with no lot, or a lot that does not match, describes some other vial.
2. The laboratory is named and has its own lookup. The report should come from a laboratory the seller does not own, with a search code you can enter on the laboratory's own site. LabFirst lots are tested by Freedom Diagnostics and looked up by accession number; anything that can only be verified on the seller's own page has not been verified.
3. The theoretical mass is printed, and it is the right one. For PT-141 that is 1024.524 Da monoisotopic; a certificate that prints a different figure has either measured a different molecule or copied a template.
4. Purity has a method and a date. An HPLC percentage should name the method and the run date. A figure that reads "99%+" with neither, or one date reused across every product a seller lists, is decoration.
5. Net content is stated in milligrams. The label size is a claim; the certificate's net content is the measurement. If the certificate has no net content line, the purity figure describes the powder, not the vial, and the price per mg you calculated is fiction.

How listings for PT-141 specifically mislead:

• Melanotan II shipped as PT-141. It is the amide, one dalton lighter and cheaper to make; only a certificate that prints the mass to a decimal place separates the two.
• "Same as Vyleesi" or "pharmaceutical grade". Vyleesi is an approved product with a release specification; a research vial has a lot certificate and nothing else, and no equivalence is claimed or possible.
• A certificate with a mass 18 Da high. That is the linear precursor whose lactam ring never closed, a different compound; the purity figure beside it describes the wrong molecule.
• "99.5%" with no oxidation peaks named. A tryptophan-containing peptide ages in a known way; a certificate that never sees +16 or +32 Da peaks on PT-141 may never have looked.

How to verify a LabFirst PT-141 lot

The PT-141 sizes in stock today carry lot LF-2608-21. Lot LF-2608-21 is at Freedom Diagnostics on accession FD-2026-05716 for identity, purity and net content. Until the report is attached the product page says "pending verification" against that lot and makes no purity claim; the price stands and the report goes live the day it arrives, on the page, at /coa/, and inside the receipt and packing slip for every order of that lot.

Verification runs through the laboratory, not through us. Open the certificate index, find the lot, and use the accession number on the Freedom Diagnostics lookup page; the report you see there is the laboratory's copy, not ours. Each lot also carries a Finnrick verify link, and every receipt and packing slip states that a customer may submit a sealed vial to Finnrick's free testing programme with the order as proof of purchase, so the brand's public record is built from vials we did not choose.

The product page reads the live stock feed on load (stock, lot and certificate state for every size), so what you see when you order is what ships. The lot is printed on the label and encoded in the QR patch on its right-hand side; scanning it opens that lot's record.

Storage and shipping for PT-141

Tryptophan is the storage story: the indole ring oxidises with light and air, slowly in the sealed dry cake at 2 to 8 C in the dark and quickly in a solution left on a lit bench, so a prepared PT-141 solution is kept cold and dark, dated, and used inside the laboratory's own stability record rather than any figure on a label. The lactam ring is robust once formed, the histidine and arginine are stable, and there is no cysteine or methionine. The dry cake's other enemy is water drawn from humid air once the vial is opened, which a peptide salt takes up readily; open a vial once, for its purpose, and never re-seal one for storage.

Orders ship within the United States, flat $15 under $200 and free above it, same day when placed before 12 PM Pacific on a business day, and the shipping page states the cutoff, the carriers and what is and is not promised.

The record a laboratory keeps on arrival is what makes the certificate usable later, and it is short:

• the lot number as printed on the vial, and the certificate's accession or search code beside it;
• the date received and the condition of the seal;
• the storage location and temperature it went into;
• the number of vials, and later the date each one was opened and by whom.

A PT-141 vial with that record behind it can be traced from the bench to the laboratory report in one step; without it, the certificate is a document about a vial that can no longer be identified.

Regulatory status, and what this page is not

Bremelanotide is the active ingredient of an approved medicine, Vyleesi (2019), whose prescribing information is cited below. That approval belongs to that product and its manufacturing, and it confers nothing on a research vial: the PT-141 sold here is not made under it, is not tested to its specification and is offered as laboratory material only, with no claim that it is equivalent to, as pure as, or a substitute for any medicine. There is no USP monograph for the bulk peptide that a research lot could claim to meet, and the closely related Melanotan II, which is not approved anywhere, sits on Category 2 of the FDA's 503A list, which is a further reason to read the certificate's decimal place.

FOR LABORATORY AND IN-VITRO RESEARCH USE ONLY. NOT FOR HUMAN OR ANIMAL CONSUMPTION. LabFirst sells PT-141 to laboratories and researchers as material for in-vitro work, gives no guidance on use, and ships only against that understanding. Nothing on this page or on the product page describes preparing or administering anything.

What is PT-141 studied for?

Published research on PT-141 investigates the areas below — which is a different question from what PT-141 will do for anyone, a claim about a living system that nothing on this site is sold for.

What it is. A man-made ring-shaped peptide seven building blocks long that works on melanocortin receptors, also published as bremelanotide.

What the research looks at. A registered clinical record exists, and an approved medicine containing bremelanotide exists under its own brand name for one specific use in a defined group of people.

How it is thought to work. It switches on melanocortin receptors, with reported activity at MC4R. It came out of a breakdown product of melanotan II and is a chemically different molecule from it.

What is not established. What is sold here is a research chemical and not a drug product. Listing it is not an approval, an equivalence or a safety claim, and this record does not describe use in a person.

The full record, including the certificate for the lot in stock, is on the PT-141 product page.

Common questions

Sources

• PubChem, Bremelanotide, CID 9941379. Public record for the molecular formula (C50H68N14O10), average molecular weight (1025.2 Da) and monoisotopic mass (1024.524 Da) quoted here as the identity reference.
• Diamond and colleagues, An effect on the subjective sexual response in premenopausal women with sexual arousal disorder by bremelanotide (PT-141), a melanocortin receptor agonist, Journal of Sexual Medicine 2006. Primary description of the compound in the literature; supports the class and naming stated here, not any use.
• Hedlund, PT-141 Palatin, Current Opinion in Investigational Drugs 2004. Primary description of the compound in the literature; supports the class and naming stated here, not any use.
• FDA, Vyleesi (bremelanotide) prescribing information, 2019 2019-06. The approved product's label; cited to show that the approved medicine and the research peptide are different things with different evidence behind them.
• ICH Q2(R2), Validation of Analytical Procedures (2023) 2023-11. Why a purity figure is only interpretable with its method, and what "fit for purpose" means for the HPLC and mass spectrometry results a certificate reports.
• Freedom Diagnostics, certificate lookup by accession number. The laboratory-side lookup a LabFirst lot is verified on; the report there is the laboratory copy, not ours.
• Finnrick, verify a vendor or lot. Independent verification page linked from every LabFirst lot; customers may submit sealed vials with their order as proof of purchase.